Will a Damaged CV Boot Fail an MOT?
It can, but the condition of the gaiter determines the MOT result. A CV boot that has deteriorated badly but still protects the joint is currently treated differently from a boot that has split, disappeared or moved out of position enough to leave the joint exposed to contamination.
The CV joint itself is also inspected separately. If the joint has already become excessively worn, replacing only the rubber boot will not remove the underlying transmission defect.
Severe Boot Deterioration
Pass PossibleA heavily aged or deteriorated CV boot can be recorded as Minor while it still remains effective enough to protect the joint.
Protection Has Been Lost
MOT FailureA boot that is split, missing or insecure enough that road dirt can reach the joint moves into the Major category.
CV Joint Excessively Worn
MajorExcessive wear in the transmission joint is a separate failure route, even if a new boot has already been fitted.
Grease splatter can help reveal a failed gaiter or clamp. Wiping the area clean before the test does not restore the boot's seal, replace lost lubricant or remove contamination already inside the joint.
A gaiter caught while the CV joint is still smooth and quiet may only require a boot repair. If the vehicle has been driven for some time with grease loss and contamination, the repair decision can move towards a CV joint or complete driveshaft.
CV Boot, CV Joint & Driveshaft MOT Defects Explained
A useful way to understand the MOT is to separate the protective gaiter from the transmission parts underneath it. The boot has its own defect levels, while the joint, shaft, bearings and associated transmission components are inspected under separate criteria.
| Condition | Current Classification | MOT Result | Practical Meaning |
|---|---|---|---|
| CV boot badly deteriorated but still protecting joint | Minor | Pass possible | Repair before deterioration progresses into an open or insecure gaiter. |
| CV boot missing | Major | Fail | Joint no longer has the protection the boot is designed to provide. |
| CV boot split and no longer protecting joint | Major | Fail | Replace the boot and inspect the joint for grease loss and contamination. |
| CV boot insecure and joint exposed to dirt | Major | Fail | Check clamps, boot seating and whether the gaiter itself is damaged. |
| Transmission joint excessively worn | Major | Fail | Boot replacement alone will not correct excessive CV-joint wear. |
| Transmission condition likely to fail | Dangerous | Fail | Serious driveline condition requiring repair before further normal driving. |
| Transmission shaft bent or badly damaged | Major | Fail | Inspect the complete driveshaft rather than concentrating only on the gaiter. |
Grease around the wheel arch, suspension or gearbox side of the driveshaft can point directly towards a torn or displaced gaiter. The MOT decision, however, is based on the actual boot and transmission condition rather than creating a separate category simply because grease is visible.
If contamination has already damaged the joint and excessive play or wear remains, the transmission fault still needs repair. This is why diagnosis must go beyond replacing the visible rubber gaiter.
What Does the MOT Tester Check Around the CV Boot and Driveshaft?
The tester does not inspect the CV boot as an isolated rubber part. The transmission inspection covers the driveshaft, its joints, bearings, securing points and protective CV gaiters.
Is the Boot Deteriorated?
Cracking, ageing and deterioration are assessed to establish whether the gaiter remains effective or has progressed into a more serious defect.
Has the Boot Opened Up?
A split becomes particularly significant once the opening means road dirt and water can reach the CV joint.
Is the Boot Still Secured?
A displaced gaiter or failed clamp can leave an otherwise intact boot unable to seal correctly around the joint or shaft.
Is the Joint Excessively Worn?
Excessive transmission-joint wear is assessed separately from the gaiter and can cause a Major failure in its own right.
Is the Shaft Secure and Sound?
Driveshaft security, damage and associated bearings are part of the wider transmission inspection.
Is Failure Becoming Likely?
Transmission deterioration can move beyond ordinary wear into a Dangerous condition when mechanical failure is considered likely.
The tester decides which defect level matches the observed condition. A technician then needs to determine why the boot failed, how long the joint may have been exposed and whether the CV joint or complete driveshaft has suffered damage.
Drivers often notice outer boots first because they sit near the steering wheels and can throw grease around the wheel arch. Inner boots can fail as well and may leave grease around the gearbox side of the driveshaft.
Is a Cracked or Deteriorated CV Boot an MOT Failure?
Not automatically. A CV boot can be badly aged, cracked or deteriorated while still retaining enough integrity to protect the joint from road dirt and water.
Where the deterioration is severe but the gaiter still performs its protective job, the current MOT classification is Minor.
Fine Cracks
Small surface cracks can develop as the rubber ages, particularly in the folds that flex whenever the suspension or steering moves.
Rubber Becoming Brittle
Hardened rubber can still appear intact while becoming much more likely to split when the joint moves through its normal operating angle.
Protection Still Intact
MinorSevere deterioration can remain a Minor defect while the boot continues to seal the joint effectively against contamination.
The important change occurs when deterioration progresses far enough that the gaiter can no longer keep dirt and water away from the CV joint. That is why visible ageing should not automatically be described as the same defect as a full split.
A deteriorated boot is usually cheaper to deal with before grease is lost and contamination reaches the joint. Once the joint itself wears, the repair can become significantly more involved.
Will a Split CV Boot Fail an MOT?
A split CV boot can become a Major MOT defect when the opening means the gaiter no longer protects the constant velocity joint from dirt entering.
The important issue is therefore not simply whether a visible line or crack exists in the rubber, but whether the protective seal around the joint has actually been lost.
Surface Crack Only
A mark or crack that has not opened through the gaiter should not be automatically treated as the same condition as an exposed joint.
Gaiter Has Opened
Once the rubber has opened enough to let road contamination reach the joint, the boot has stopped doing the job it was designed to perform.
Protection Lost
MajorA split that leaves the joint without effective protection is a Major defect and causes the vehicle to fail the MOT.
Outer gaiters flex considerably as the steering turns. A split can close visually in one position and open much wider at another steering angle, so the folds need careful inspection.
Splits often start in the valleys between the rubber ribs where flexing is greatest. Grease collecting around one fold can help identify a tear that is difficult to see from above.
Will a Missing CV Boot Fail an MOT?
Yes. A CV joint that should have a protective gaiter but no longer has one is left exposed to contamination and loss of lubricant.
Where the missing gaiter means the joint has lost its protection from road dirt, the defect is Major.
No Gaiter Present
The CV joint has no flexible barrier retaining grease and shielding its working surfaces from road contamination.
Contamination Likely
A missing boot should trigger inspection of the joint itself rather than assuming fitting a new rubber gaiter is automatically enough.
Major
MOT FailureLoss of the protective gaiter is a Major MOT issue where the joint is left open to dirt ingress.
If the vehicle has been driven without a gaiter, grease may already have escaped and abrasive dirt may already be inside the joint. Check for wear, noise and contamination before deciding that a boot-only repair is enough.
Can a Loose or Insecure CV Boot Fail an MOT?
Yes, if the gaiter has become insecure enough that it no longer protects the CV joint from contamination.
A boot does not need a dramatic tear to lose its protective function. A failed clamp, displaced boot lip or incorrectly fitted replacement gaiter can open a path for grease to escape and dirt to enter.
Clip Loose or Missing
If a retaining band no longer grips the gaiter securely, the boot can slide away from its sealing surface.
Boot Has Moved
A gaiter can remain physically intact but sit partly off the joint housing or driveshaft groove.
Seal No Longer Effective
MajorOnce insecurity means contamination can reach the CV joint, the defect moves into the Major category.
A boot that has slightly shifted but still remains fully sealed is not the same mechanical condition as one that has moved far enough to expose the joint. Inspect how well the gaiter actually seals at both ends.
Incorrectly seated clamps can loosen after the first few journeys. Rechecking the boot position, clip security and grease leakage after repair can prevent an avoidable repeat fault.
Does Grease Leaking From a CV Boot Automatically Fail an MOT?
No — visible grease is evidence of a problem, not a separate MOT classification by itself.
Grease around the inside of a wheel, suspension arm, wheel arch or gearbox side of the driveshaft should prompt inspection of the gaiter, its clamps and the CV joint underneath.
Grease Around Wheel Arch
An outer CV boot rotates with the driveshaft, so escaped grease can be flung outward in a circular pattern onto nearby components.
Grease Near Gearbox Side
An inner gaiter fault may leave grease around the inner driveshaft, subframe or transmission-side components rather than the wheel arch.
Boot May Not Be Torn
Grease can escape where a clamp is loose or the gaiter has moved, even when the rubber itself has not visibly split.
Cleaning the area does nothing to restore lubricant inside the joint or seal a damaged gaiter. Find where the grease escaped, repair the cause and check whether contamination has already entered.
Thick grease thrown radially around a rotating driveshaft area often gives a useful clue about where the boot has opened. Inspect the entire gaiter and both retaining points rather than assuming the first visible wet area is the actual split.
Why Does Dirt Entering the CV Joint Matter for the MOT?
The CV boot has two linked jobs: retain the joint grease and keep abrasive road contamination outside.
Once the gaiter no longer forms an effective barrier, water, grit and road dirt can mix with the lubricant and begin damaging the precision surfaces inside the joint.
Abrasive Contamination
Fine grit mixed with CV grease can accelerate wear between the joint's moving tracks, bearings and contact surfaces.
Moisture Enters the Joint
Water can degrade lubrication and promote corrosion where the joint has been exposed for an extended period.
Protective Function Lost
MajorThe key threshold is reached when a missing, split or insecure gaiter no longer performs its protective role against dirt ingress.
The current rule links the more serious classification to a missing, split or insecure boot that has actually lost its ability to protect the joint. That prevents minor surface deterioration from being described as the same defect as an open, unsealed gaiter.
If the joint has run with little grease or with dirt inside, inspect it for roughness, clicking, excessive movement or other wear before deciding whether fitting a new gaiter is sufficient.
Can a Worn CV Joint Fail an MOT?
Yes. The CV joint is assessed separately from the protective boot. If wear in the transmission joint becomes excessive, it can be a Major MOT defect.
This is an important distinction because replacing a split gaiter does not repair a joint that has already been damaged by grease loss, dirt ingress or prolonged operation with poor lubrication.
Boot Damaged, Joint Still Smooth
If the fault is caught early, the joint may still operate quietly and without excessive movement, making a boot-only repair more realistic.
Noise or Roughness Appears
Clicking, knocking or rough movement suggests the problem may have progressed beyond the rubber gaiter itself.
Excessive Joint Wear
MajorExcessive wear in the transmission joint is a separate Major defect and needs proper mechanical repair.
If a gaiter has recently been replaced but the car still clicks, knocks or vibrates, do not assume the repair is complete. The joint may already have been damaged before the new boot was fitted.
Inspect for free play, roughness, noise and signs of contamination. The correct repair may be boot-only, joint replacement or complete driveshaft replacement depending on what is actually worn.
Does Clicking When Turning Mean the CV Joint Is Worn?
Repetitive clicking on tighter steering angles is a classic sign that an outer CV joint may already be worn.
The noise often becomes most noticeable at low speed while accelerating through a turn, because the outer joint is operating at a larger angle and carrying drive torque at the same time.
Repeated Clicks
A rhythmic clicking that repeats with wheel rotation can point towards wear inside the outer constant-velocity joint.
Louder While Accelerating
The symptom may become stronger when power is applied because the worn joint is transmitting more torque through its internal tracks.
Previous Grease Loss
A split or displaced gaiter in the past increases suspicion that the joint has operated with reduced lubrication or contamination.
The MOT treatment of the gaiter still depends on its condition and security. Clicking moves the diagnosis towards the joint underneath and whether wear has become excessive.
If the joint clicks repeatedly under steering load, simply fitting a new gaiter may protect a worn joint without restoring proper mechanical condition.
Clicking When Turning
Knocking When Turning
How Much CV Joint Play Is Too Much?
Driveline joints need enough internal movement to operate through changing angles, so the presence of some movement does not automatically mean the joint is defective.
The concern is excessive looseness, rough movement or wear that indicates the joint is no longer in serviceable condition.
Small Driveline Lash
Some rotational movement can come from normal clearance elsewhere in the gearbox, differential and driveshaft system.
Excessive Free Play
Noticeable looseness concentrated at the CV joint becomes more significant when accompanied by knocking, roughness or vibration.
Rough or Notchy Joint
A healthy joint should articulate smoothly. Binding, rough spots or obvious notchiness can indicate internal damage.
Comparing one driveshaft with the opposite side can help identify a joint that behaves very differently, although vehicle design and shaft length can create some normal variation.
Movement can exist in several components between the wheel and gearbox. Isolate the joint itself before condemning it, particularly where the only symptom is a small amount of rotational free play.
What Is the Difference Between Inner and Outer CV Boot Faults?
Most front-wheel-drive shafts have a CV joint at each end, and both joints need a protective gaiter. Their location and movement mean they often show different symptoms when wear develops.
Wheel-Side Joint
The outer joint operates through large steering angles as well as suspension movement. Its boot is therefore subjected to considerable repeated flexing.
- Clicking is more commonly associated with turning.
- Grease may be thrown around the wheel arch or inner wheel.
- Splits often appear deep in the gaiter folds.
Gearbox-Side Joint
The inner joint allows suspension movement and changes in effective driveshaft length as the wheel moves through its travel.
- Grease leakage is more likely to appear near the gearbox side.
- Wear may show as vibration or shudder under acceleration.
- The boot can fail even without obvious full-lock clicking.
The inspection principle is not limited to the outer wheel-side gaiter. Inner joint boots can also deteriorate, split or become insecure and lose their ability to protect the joint.
Clicking on turns tends to direct attention towards the outer joint, while vibration under acceleration can increase suspicion around the inner joint or another driveline component.
Can Driveshaft Damage Fail an MOT?
Yes. The transmission inspection does not stop at the CV boot or joint. The driveshaft itself, associated bearings and security are also relevant.
Once damage becomes serious enough to affect shaft condition or create a risk of transmission failure, the fault has progressed well beyond a simple protective-gaiter problem.
Bent or Badly Damaged
A shaft that has been bent by impact or damaged badly enough to affect its mechanical integrity needs direct attention.
Driveshaft Insecure
Check that the shaft and its transmission connections remain correctly located and securely retained.
Support Bearing Wear
Some longer driveshafts use intermediate support bearings, which can develop noise or movement independently of the CV joints.
Shudder Under Load
Strong vibration during acceleration can result from joint wear, driveshaft damage or another transmission problem and needs diagnosis before assuming the gaiter is the only issue.
Failure Risk Increasing
Severe transmission deterioration can move from ordinary wear into a condition where mechanical failure is becoming likely.
Dangerous Condition
Where transmission wear has progressed to a condition likely to fail, the MOT severity can become Dangerous.
A torn boot may explain how joint damage started, but once the vehicle develops strong vibration, knocking or severe looseness, inspect the complete shaft and transmission joint assembly.
Some vehicles allow the CV joint to be replaced separately. Others are more practical to repair using a complete driveshaft. The correct choice depends on joint condition, shaft condition, parts availability and labour.
What Should Be Checked After a CV Boot or Driveshaft Repair?
A CV repair is not complete simply because a new gaiter or driveshaft has been fitted. The repair should be checked for correct seating, security, grease containment and normal driveline operation.
Gaiter Seated Correctly
Both ends of the gaiter should sit correctly in their intended grooves without twisting or stretching.
Retaining Bands Secure
Loose clamps can allow grease to escape or the boot to move after only a short period of driving.
No Fresh Leakage
After cleaning the old grease away, recheck for fresh leakage around the boot and clamp areas.
No Clicking or Roughness
A new boot should not be considered a complete repair if the underlying CV joint still clicks, knocks or operates roughly.
No Abnormal Vibration
Road-test evidence should confirm that the shaft and joints operate smoothly under acceleration and steering load.
Recheck Before MOT
Before presenting the car for test, confirm the gaiter remains sealed, secure and free from fresh grease leakage.
If a newly fitted boot quickly throws grease again, check clamp tension, boot seating, the correct gaiter size and whether excessive joint or shaft movement is disturbing the repair.
The gaiter should seal correctly and the joint should remain smooth, quiet and serviceable. That is the difference between replacing a visible rubber part and actually restoring the driveline fault.
What Should You Check Before the MOT if a CV Boot Looks Damaged?
A useful pre-MOT check should establish whether the problem is still limited to the protective gaiter or whether there is evidence that the CV joint or driveshaft has already been affected.
The safest approach is to inspect boot condition, clamp security, grease loss, joint noise and driveline behaviour together.
Inspect the Gaiter Folds
Look for cracking, splits and hardened rubber, especially in the folds where the boot flexes most.
Check Both Clamps
Confirm the boot remains seated securely at both ends and has not moved away from the joint housing or driveshaft.
Look for Fresh Grease
Grease around the wheel arch, suspension or inner driveshaft can reveal an opening that is difficult to see directly.
Listen on Tight Turns
Repeated clicking while driving slowly on steering lock can indicate outer CV-joint wear rather than a boot-only problem.
Note Acceleration Vibration
Shudder or vibration under load can move suspicion towards an inner CV joint, driveshaft or another transmission component.
Review Previous MOT Advisories
A gaiter noted previously as deteriorated may have progressed into a split or insecure condition by the next test.
Carry out visual checks only with the vehicle safely stationary and supported correctly. Joint play and driveshaft condition should be assessed using appropriate workshop procedures.
A boot can look untidy but still protect the joint, while a cleaner-looking gaiter can have a hidden split deep inside one of its folds. Inspect the full circumference where access allows.
How Should a CV Boot and Joint Fault Be Diagnosed?
The diagnosis should answer one central question: is this still a protective-boot repair, or has the transmission joint already been damaged?
Confirm Boot Condition
Identify whether the gaiter is merely deteriorated or whether it is genuinely split, missing or displaced.
Assess the Seal
Check whether both ends remain secure and whether the boot still prevents contamination reaching the joint.
Check Grease Loss
Establish how much lubricant has escaped and whether the joint has likely operated with reduced grease.
Inspect for Contamination
Dirt, water or gritty grease inside the joint increases the likelihood that a boot-only repair will be insufficient.
Check Joint Movement
Assess for excessive free play, roughness, notchiness or other evidence of mechanical wear.
Road-Test the Symptoms
Where safe and appropriate, use clicking, knocking or acceleration vibration to help identify whether the outer or inner joint is affected.
Grease loss proves that the protective system needs attention, but the joint may still be healthy if the fault was caught early. Confirm its actual condition before replacing more parts than necessary.
Clicking, excessive play or roughness after gaiter replacement means the mechanical wear still needs diagnosis.
What Should Be Repaired Before Presenting the Car for MOT?
The correct repair depends on how far the fault has progressed. Repair the actual condition rather than merely cleaning the evidence away.
Deteriorated Boot
Repairing the gaiter before it splits can prevent contamination and reduce the chance of a later MOT failure.
Split or Open Gaiter
Replace or correctly repair the boot and inspect the CV joint before presenting the vehicle for test.
Insecure Boot
Restore correct seating and clamp security so the gaiter again protects the joint from contamination.
Excessive CV Wear
Replace the worn joint or complete shaft as appropriate rather than fitting only another protective boot.
Bent or Badly Damaged Driveshaft
Repair or replace the shaft if structural damage rather than gaiter condition is the real problem.
Transmission Likely to Fail
This is not a routine pre-MOT tidy-up. Serious driveline deterioration needs repair before further normal driving.
A temporary wrap does not restore the original sealing, flexibility or clamp security of the gaiter and does not address contamination already inside the joint.
CV Boot vs CV Joint vs Complete Driveshaft: What Should Be Replaced?
The cheapest repair is only the best repair when it matches the condition of the joint underneath.
Joint Still Healthy
A gaiter-only repair makes sense when the joint remains smooth, quiet and free from excessive wear or contamination.
Joint Already Worn
Where the joint is available separately and wear is confirmed, replacing the joint can restore the shaft without replacing every component.
More Practical Replacement
On some vehicles, a complete driveshaft is quicker or more economical than dismantling an old shaft to replace one joint.
| Finding | Likely Repair | Reason |
|---|---|---|
| Deteriorated boot, no noise or play | CV boot replacement | Joint appears serviceable |
| Split boot, recently caught, joint clean | Boot + correct grease | Protection can be restored early |
| Split boot with clicking or excessive wear | CV joint or driveshaft | Mechanical damage has progressed beyond gaiter |
| Driveshaft bent or badly damaged | Complete driveshaft | Shaft itself is no longer serviceable |
A boot kit is inexpensive, but replacing it often requires significant dismantling. On some vehicles a complete replacement shaft can therefore be financially competitive with a joint-only repair.
How Much Does CV Boot, Joint or Driveshaft Repair Cost in the UK?
These are practical Motor Vehicle Expert planning ranges rather than fixed quotations. Vehicle design, inner versus outer location, part quality and how much dismantling is required can change the final bill.
CV Boot Replacement
£100–£220Typical planning range where the joint remains serviceable and only the gaiter, clamps and grease need attention.
CV Joint Replacement
£150–£350Common planning range where the joint itself has become noisy or worn but can be replaced separately.
Driveshaft Replacement
£200–£700+The price rises on premium, performance, four-wheel-drive or complex vehicles where shafts and labour are more expensive.
| Repair | Planning Cost | Best Fit | What Should Confirm It |
|---|---|---|---|
| CV boot | £100–£220 | Joint still healthy | No excessive play, clicking or roughness |
| CV joint | £150–£350 | Joint worn but shaft serviceable | Noise, wear or play isolated to joint |
| Complete driveshaft | £200–£700+ | Shaft/joint assembly replacement | Joint or shaft damage and vehicle-specific parts economics |
Paying for a boot-only repair on a joint that already clicks or has excessive wear can mean paying labour twice when the joint or shaft needs replacing shortly afterwards.
Current UK price benchmarks consistently show boot-only work below the cost of CV-joint or complete driveshaft replacement. Catching the gaiter fault before the joint wears is therefore usually the least expensive route.
What Happens After a CV Boot or Driveshaft MOT Failure?
Repair the failed transmission defect first, then use the appropriate partial-retest arrangement.
Retested Within 10 Working Days
No Retest FeeIf the vehicle remains at the same test centre for repair and is retested within 10 working days, only a partial retest is required and there is no additional retest fee.
Return Within 10 Working Days
Partial Fee Can ApplyIf the vehicle is repaired elsewhere and returned to the same test centre within 10 working days, a partial retest can still be carried out but a partial fee may be charged.
Full MOT Required
Outside the qualifying retest period, the vehicle generally needs a full MOT test again.
Do not assume that taking the car away, replacing a gaiter and returning the next working day automatically makes the partial retest free. The normal retest arrangements above apply.
If the CV joint or transmission has deteriorated to the point that mechanical failure is possible, do not treat the remaining MOT validity as permission to continue normal driving.
Should You Buy a Used Car With a Split CV Boot?
A damaged CV boot is not automatically a reason to reject a used car. The important question is whether the fault is still a relatively simple gaiter repair or evidence of joint and driveshaft wear.
Look for Fresh Grease
Heavy grease around the wheel arch or inner shaft can suggest the boot has been open for some time.
Listen for Clicking
Repetitive clicking on tighter turns increases suspicion that an outer joint is already worn.
Watch for Vibration
Shudder or vibration under load can point towards an inner joint, driveshaft or another transmission fault.
Check Repeat Gaiter Advisories
Repeated deterioration notes can show that a cheap preventative repair has been postponed over several tests.
Ask What Was Replaced
If the seller says the CV boot was repaired, establish whether the joint was also inspected for wear and contamination.
Allow for the Correct Repair
Do not negotiate on a boot-only price if clicking, play or driveline vibration suggests the repair may actually need a joint or shaft.
Inspect the gaiter itself, both clamps and the surrounding components rather than relying on how clean the area looks during the viewing.
If the joint remains smooth and quiet, there is no excessive play and the repair cost is reflected in the price, a gaiter fault can be much less concerning than an already noisy driveshaft.
Check Previous Tests
Listen Under Load
Check the Whole Vehicle
CV Boot, Driveshaft & Steering MOT Guides
Use the guide that matches the actual fault. CV gaiter deterioration, CV-joint wear, wheel-bearing play, steering-joint wear and suspension movement are separate problems even when the symptoms appear in the same wheel or driveshaft area.
CV Boot & Gaiter Rules
This page owns the MOT distinction between deterioration, a split or insecure gaiter, contamination protection and joint wear.
Clicking When Turning
Use this symptom guide when the concern has moved from the gaiter to possible outer CV-joint wear.
Bearing Play & MOT
Wheel-bearing noise and free play can appear near the same area but require a separate inspection and MOT interpretation.
Suspension Joint Wear
Ball-joint play can create knocking, movement and steering symptoms that should not be confused with CV-joint wear.
Track Rod End MOT
Steering-joint wear can create looseness and tyre-wear symptoms close to the same front-wheel area.
Lower Arm & Suspension
Lower-arm bushes, ball joints and suspension security need their own diagnosis rather than being grouped into a generic driveshaft fault.
Clicking, knocking, vibration and wheel-area movement can come from several components. Confirm whether the fault is the gaiter, CV joint, wheel bearing, steering joint or suspension before approving parts.
More UK MOT & Driveline Guides
Continue with the guide that best matches the next question: noise, suspension, MOT preparation, used-car history or wider vehicle diagnosis.
Prepare for the MOT
Work through common pre-test checks before presenting the vehicle.
Common Failure Reasons
Compare common suspension, steering, tyre, brake and lighting failure routes.
Knocking When Turning
Use this when the symptom is a knock rather than the repetitive click more commonly associated with outer CV-joint wear.
Check MOT History
Previous gaiter, driveshaft or suspension advisories can show whether a fault has been deferred across several tests.
Test Drive Properly
Listen for clicking, knocking and vibration under steering and acceleration load.
Diagnose the Vehicle
Use the Motor Vehicle Expert diagnostic tools when the symptom extends beyond a specific CV boot or MOT question.
CV Boot & MOT FAQs
Can a CV boot fail an MOT?
Yes. A CV boot can affect the MOT, but the classification depends on its condition. Severe deterioration is currently a Minor defect, while a boot that is missing, split or insecure and no longer keeps dirt away from the CV joint is a Major defect.
Will a split CV boot fail an MOT?
A split CV boot becomes a Major MOT defect when the damage means the boot no longer protects the joint from dirt entering. A superficial defect that has not reached that level should not automatically be described as the same failure.
Will a cracked CV boot fail an MOT?
Cracking does not automatically mean a Major failure. A badly deteriorated boot can be recorded as Minor, while deterioration that progresses until the gaiter no longer protects the joint from contamination can move into the Major category.
Is a severely deteriorated CV boot an MOT failure?
Severe CV boot deterioration is currently classified as a Minor defect when the boot still provides the required protection. A Minor defect can appear on a passing MOT result, but deterioration should be repaired before the gaiter splits or loses its seal.
Will a missing CV boot fail an MOT?
Yes. A missing CV boot that leaves the constant velocity joint without its normal protection against dirt is a Major MOT defect and causes the vehicle to fail.
Will a loose or insecure CV boot fail an MOT?
It can. If an insecure CV boot has moved enough that it no longer seals the joint against dirt and contamination, the defect is Major. A loose clamp or displaced gaiter should therefore be repaired before the test.
Does grease leaking from a CV boot automatically fail an MOT?
Grease leakage is useful evidence that a CV boot or clamp may be damaged, but grease on its own is not the separate defect classification. The tester assesses the boot condition and whether it still protects the CV joint from contamination.
Why does dirt getting into a CV joint matter for the MOT?
The CV boot exists to retain lubricant and protect the joint from road dirt and water. Once a split, missing or insecure boot no longer provides that protection, the current MOT treatment moves beyond simple deterioration and into a Major defect.
Does clicking when turning mean the CV boot will fail the MOT?
Clicking when turning does not classify the boot itself, but it can indicate that an outer CV joint has already worn. The joint then needs its own inspection because excessive transmission-joint wear is a separate Major MOT defect.
Can a worn CV joint fail an MOT?
Yes. Excessive wear in a transmission joint is a Major MOT defect. This is separate from the condition of the protective CV boot, so replacing the gaiter alone will not repair a joint that has already developed excessive wear.
Can a driveshaft fault be Dangerous on an MOT?
Yes. Transmission defects can reach Dangerous severity when wear has progressed to the point that failure is considered likely. Driveshaft security, bearings, joints and the shaft itself are assessed separately from the CV boot.
Can an inner CV boot fail an MOT?
Yes. The MOT principle applies to constant velocity joint boots on the transmission shaft, so an inner gaiter can be relevant just as an outer gaiter can. The classification depends on deterioration, security and whether the boot still protects the joint.
Can an outer CV boot fail an MOT?
Yes. Outer CV boots are commonly exposed to large steering angles and can crack or split over time. Severe deterioration can be Minor, while a split, missing or insecure boot that no longer protects the joint from dirt is Major.
Can you drive with a split CV boot?
The vehicle may still move normally with a split boot, but continued driving allows grease to escape and contamination to enter the joint. Repairing the gaiter early can prevent the fault progressing into CV-joint wear, noise and a more expensive repair.
Can I just add grease to a split CV boot?
No. Adding grease does not restore a damaged gaiter's ability to seal the joint. A split, missing or insecure boot needs to be repaired or replaced correctly, and the joint should be checked for contamination and wear.
Should I repair a damaged CV boot before the MOT?
Yes. Repairing deterioration before it becomes a full split can protect the CV joint and reduce the chance of an MOT failure. If grease has escaped or dirt has entered, the joint should also be inspected before fitting a new boot.
How much does CV boot repair cost in the UK?
CV boot repair cost varies with the vehicle, boot location and labour required to remove or separate the driveshaft. A boot-only repair is usually less expensive than replacing a worn CV joint or complete driveshaft, so early diagnosis can reduce the total repair cost.
Should you buy a used car with a split CV boot?
A split CV boot is not automatically a reason to reject a used car, but the CV joint should be checked for clicking, excessive play, grease loss and contamination. A cheap gaiter repair can become a more expensive joint or driveshaft repair if the fault has been ignored.