Use the diagnostic app for car noises
You can use the free Motor Vehicle Expert diagnostic app to narrow down car noises by sound, driving condition, warning lights and safety risk. It is useful when you are not sure whether the noise sounds like brakes, suspension, wheel bearing, engine, exhaust or drivetrain.
Identify the sound
Compare knocking, grinding, clicking, humming, rattling, squealing and whining noises.
Match the driving condition
Check whether it happens when braking, turning, accelerating, idling, starting or driving at speed.
Understand urgency
Separate mild noises from safety-related sounds that need urgent inspection.
Find related guides
Use linked guides for brakes, wheel bearings, steering, suspension, exhaust and engine symptoms.
Quick answer
A grinding noise often points to brakes, wheel bearings or metal-on-metal contact. A clicking noise when turning often points to a CV joint, driveshaft or steering component. A humming noise that gets louder with speed may be tyre noise or a wheel bearing. A rattling noise on startup can be timing chain, exhaust, heat shield, belt or pulley related.
If the noise is sudden, loud, getting worse, linked with braking or steering, or appears with warning lights, smoke, overheating, burning smells or fluid leaks, stop safely and get the vehicle checked.
A quiet noise that stays the same still needs checking, but a loud grinding, knocking, scraping or steering/brake-related noise should be treated as urgent.
Common car noises and what they may mean
Knocking noise
Can come from suspension joints, steering parts, engine mounts, engine faults or drivetrain wear.
Knocking when turning →Grinding noise
Often linked to brakes, wheel bearings, drivetrain components or metal-on-metal contact.
Brakes grinding guide →Clicking noise
Clicking while turning is commonly linked to CV joints, driveshafts or steering parts.
Clicking when turning →Humming or droning
Often tyre noise or wheel bearing noise, especially if it gets louder with road speed.
Wheel bearing noise →Squealing noise
Can be brakes, belts, pulleys or dry components depending on when it happens.
Brake warning signs →Whining noise
May relate to belts, alternator, power steering, gearbox, wheel bearings or turbo noise.
Whining when accelerating →Rattling noise
Can be exhaust heat shields, timing chain, loose trim, suspension or engine components.
Timing chain rattle →Blowing noise
A loud blowing sound can point to an exhaust leak, split flexi pipe or damaged exhaust section.
Exhaust blowing noise →When the noise happens matters
The same noise can mean different things depending on when it happens. A knock over bumps is different from a knock under acceleration. A hum at speed is different from a squeal when braking. Try to match the sound with the situation.
When accelerating
Can point to engine, gearbox, turbo, exhaust, driveshaft, clutch or mount issues.
Acceleration noise guide →When braking
Often brake pads, discs, calipers, wheel bearings or suspension movement.
Car shakes when braking →When turning
Often CV joints, steering components, suspension joints or wheel bearings.
Turning noise guide →At high speed
Often tyres, wheel balance, wheel bearings, loose undertrays or drivetrain noise.
High-speed vibration →At idle
Can be engine mounts, misfire, belts, pulleys, exhaust leaks or timing chain noise.
Car vibrates at idle →On startup
Can be belts, starter motor, timing chain, lifters, exhaust or battery-related strain.
Startup rattle guide →Brake noises
Brake noises should be taken seriously because they affect stopping performance. Grinding, scraping or squealing while braking can mean worn pads, damaged discs, sticking calipers, a loose backing plate or debris caught near the brake.
- !Grinding when braking: may mean pads are badly worn or metal is contacting the disc.
- !Squealing: can be pad wear, brake dust, glazing, dry contact points or low-quality pads.
- !Scraping: may be a stone, backing plate, brake hardware or disc corrosion.
- !Vibration when braking: may point to discs, pads, hubs, suspension movement or wheel bearing play.
Useful guides: brakes grinding when driving, brake warning signs, brake pad replacement cost UK and car fails MOT on brakes.
Noises when turning
Noises when turning often come from the front end of the car. Clicking can point to CV joints, knocking can point to suspension or steering wear, and humming that changes through corners may suggest a wheel bearing.
Clicking
Often CV joint or driveshaft related, especially on full lock or when pulling away.
Clicking guide →Knocking
Often suspension joints, bushes, drop links, top mounts, lower arms or steering components.
Knocking guide →Humming
May point to a wheel bearing if the noise changes when cornering left or right.
Wheel bearing guide →Engine and exhaust noises
Engine noises can be harmless or serious depending on the sound. A brief rattle on startup is different from a loud internal knock, misfire, blowing exhaust or metallic grinding noise.
- ✓Rattle on startup: timing chain, oil pressure delay, belt, pulley or heat shield issue.
- ✓Misfire sound: uneven running, shaking, popping, hesitation or poor acceleration.
- ✓Blowing noise: exhaust leak, damaged flexi pipe, loose joint or cracked exhaust section.
- ✓Whining noise: belt, pulley, alternator, turbo, gearbox or power steering issue.
Useful guides: engine misfire symptoms, car exhaust blowing noise, timing chain rattle, alternator not charging signs and car losing power when accelerating.
Suspension and steering noises
Suspension and steering noises often show up over bumps, when turning, during parking manoeuvres or when the car changes direction. These noises should not be ignored because loose or worn steering and suspension parts can affect control and MOT results.
Clunk over bumps
Often drop links, ball joints, bushes, shock absorbers, top mounts or lower arms.
Suspension MOT guide →Knock when turning
Can point to steering joints, CV joints, top mounts, ball joints or lower arms.
Ball joint MOT guide →Heavy steering noise
May involve power steering fluid, pump, belt, steering rack or electric steering fault.
Power steering warning →Wheel bearing and tyre noises
A worn wheel bearing often makes a humming, droning or growling noise that gets louder with speed. Tyres can also create humming or rumbling noises, especially if they are worn unevenly, stepped, damaged or incorrectly inflated.
- ✓Wheel bearing clue: humming gets louder with road speed and may change when cornering.
- ✓Tyre clue: noise changes with road surface or tyre condition.
- !Urgent clue: rumbling with wheel play, vibration or poor handling needs inspection quickly.
Useful guides: wheel bearing noise speeding up, wheel bearing replacement cost UK, can wheel bearing fail MOT? and can low tyre tread fail MOT?.
When to stop driving because of a noise
- !Loud grinding, scraping, banging or metallic noise.
- !Noise appears with brake warning, oil warning, overheating or steering warning.
- !Steering feels loose, heavy, notchy or unpredictable.
- !The car pulls sharply, shakes badly or feels unstable.
- !There is smoke, burning smell, coolant smell or fluid leaking.
- !The noise gets worse very quickly.
- !The noise started immediately after hitting a pothole, kerb or road debris.
If safety is in doubt, stop in a safe place and arrange recovery or professional inspection. A noise that involves brakes, steering, tyres or suspension should be treated more seriously than a minor trim rattle.
What to tell the garage
A clear description helps the garage find the fault faster. Try to note the sound, when it happens, where it seems to come from and whether anything else changed at the same time.
- ✓What the noise sounds like: knocking, grinding, clicking, humming, squealing, rattling or whining.
- ✓When it happens: accelerating, braking, turning, idling, cold start or high speed.
- ✓Where it seems to come from: front, rear, left, right, engine bay or underneath.
- ✓Whether warning lights, smells, smoke, vibration or poor handling appear too.
- ✓Whether it started after repairs, tyre changes, brake work, pothole impact or a long journey.
Common mistakes drivers make
- !Ignoring brake grinding because the car still stops.
- !Assuming every humming noise is tyres without checking wheel bearings.
- !Replacing parts based only on the sound without checking when the noise happens.
- !Driving for weeks with a noise that is getting louder.
- !Forgetting to mention recent repairs, pothole impact or warning lights to the garage.
- !Waiting until MOT day to investigate obvious suspension, steering, exhaust or brake noises.
Best mechanic-style advice
Do not diagnose a car noise by sound alone. Match the sound with when it happens. A clicking noise on full lock, a grind when braking, a hum that rises with speed and a rattle on cold startup all point in different directions.
The safest approach is to treat brake, steering, suspension, wheel bearing and loud metallic noises as priority checks. Minor rattles can still be annoying, but safety-related noises should be dealt with before they become more expensive or dangerous.
Related diagnostic guides
Frequently asked questions
Why is my car making a grinding noise?
Grinding often points to brakes, wheel bearings, drivetrain components or metal-on-metal contact. Grinding when braking should be checked urgently because braking performance may be affected.
Why is my car making a clicking noise when turning?
Clicking when turning is commonly linked to CV joints, driveshafts, steering parts or suspension components, especially if it happens on full lock.
Why does my car hum louder as I speed up?
A humming noise that gets louder with road speed is often tyre noise or a wheel bearing. If it changes when cornering, a wheel bearing should be checked.
Why is my car rattling on startup?
Startup rattles can come from timing chains, belts, pulleys, heat shields, exhaust parts, starter motor issues or oil pressure delays.
Can I keep driving with a strange car noise?
Only if the noise is mild, stable and not linked to braking, steering, warning lights, smoke, smells or poor handling. Loud, sudden, worsening or grinding noises should be checked quickly.
Can car noises fail an MOT?
The noise itself may not be the MOT failure item, but the cause can fail if it involves brakes, suspension, steering, tyres, wheel bearings, exhaust leaks or insecure components.
Is a knocking noise dangerous?
It depends where it comes from. Knocking from suspension, steering, engine or drivetrain parts should be checked, especially if it gets worse or affects handling.
Is a squealing brake noise serious?
Sometimes it is minor brake dust or glazing, but it can also mean pad wear or brake hardware problems. If the noise is constant, loud or comes with poor braking, get it checked.