Yes, an indicator can fail an MOT in the UK if it is not working, flashes incorrectly, shows the wrong colour, is insecure, obscured or incorrectly positioned on the vehicle.
An indicator can fail an MOT if a required lamp does not work, flashes at the wrong speed, stays on solid, shows the wrong colour, is insecure or is badly affected by a cracked lens, poor wiring or water ingress.
Hazard warning lights also need to work correctly where required. If hazards only flash on one side, miss a lamp or flash irregularly, the fault should be repaired before the test.
Indicators help other drivers, cyclists and pedestrians understand your next move. A failed indicator can make lane changes, roundabouts, junctions and parking manoeuvres more risky.
These are the indicator faults most likely to cause a failed test.
One or more required indicators fail to illuminate when operated.
Rapid flashing often points to a failed bulb, LED fault, wiring issue or incorrect resistance.
Hazards should flash the required indicator lamps together where fitted and required.
Indicators should show the correct amber signal colour. Faded lenses or wrong bulbs can cause problems.
A cracked, missing or faded lens can affect visibility, colour or lamp security.
A lamp that is hanging loose, insecure or water-damaged can fail.
Most indicator faults are electrical or lamp-related, but the exact cause depends on the vehicle.
Still common on vehicles with replaceable indicator bulbs.
Incorrect bulb type, colour or wattage can affect flash rate and brightness.
Bad earths can cause dim lights, fast flashing or strange rear lamp behaviour.
Moisture inside the lamp can corrode bulb holders, plugs and LED units.
The indicator stalk may fail, cancel incorrectly or only work in one direction.
Some modern cars need a complete lamp unit if the LED section fails.
Do this with the car safely parked and the ignition on if needed.
Check the front, rear and side repeater on the left side if fitted.
Check the front, rear and side repeater on the right side if fitted.
All required indicator lamps should flash together and consistently.
Fast flashing, slow flashing or one side behaving differently usually means a fault.
Look for cracks, missing pieces, faded amber sections or water inside the lamp.
Some cars show bulb failure messages or flash the dash symbol faster when a lamp is out.
Many indicator faults are caused by bulbs, bulb holders, corroded plugs, bad earths or damaged lenses. These are usually worth sorting before the MOT because lighting failures are avoidable.
If a bulb has failed, check the lens and holder too. A new bulb may fail again if water is getting into the lamp or the contacts are corroded.
On some newer vehicles, the indicator is built into a headlight, tail light or mirror repeater. If the LED section fails, the repair may involve a full lamp or mirror unit rather than a simple bulb.
That is why diagnosis matters before buying parts.
These faults can be missed because they do not always show from the driver’s seat.
Side repeaters in mirrors are easy to forget during a quick check.
The indicator may make other rear lights dim, flash or behave strangely.
The lamp works, but the colour may no longer be clear enough.
One side may flash normally while another lamp is dead.
Moisture can make bulbs intermittent and damage LED units.
A wrong bulb can change brightness, colour or flash rate.
Common questions about indicators, side repeaters, hazards, flash rate and damaged lenses.
Yes, if it is a required indicator lamp and it does not work correctly.
Fast flashing usually means a failed bulb, LED fault, bad connection or resistance issue.
Yes. Where fitted and required, side repeaters should operate correctly.
Yes, if the damage affects colour, visibility, security or exposes the lamp.
Yes. Hazard lights are a sensible pre-MOT check and should flash correctly.
Yes. LED indicators must still function correctly, even if the repair is different from a bulb replacement.
Motor Vehicle Expert publishes practical UK-focused vehicle diagnostics, maintenance, MOT, used car and repair cost guidance based on common driver questions and real-world garage situations.
