Tyres  /  Tyre News /  Help and Advice  / How Faulty Side Repeaters Can Lead to MOT Failure

Side repeaters are often forgotten about regarding an MOT test, but this function of your car should not be overlooked.

Once your annual MOT is just round the corner, you should ideally have everything in working order. However, if parts of your vehicle are not roadworthy – including your side repeaters – your car could fail its test.

These small but important indicators are vital for signalling your intentions to other road users, and if they’re not functioning correctly, it can compromise safety and may result in an MOT failure.
 

What is a Side Repeater?

Side repeaters are small indicator lights typically located on your vehicle’s front wings, wing mirrors, or just behind the front wheel arch.

Their main function is to improve the visibility of your signalling intentions to other road users – especially those driving or standing side-on to your vehicle.

They work in conjunction with your main indicators, flashing simultaneously to signal a turn or lane change.

By increasing the angle of visibility, side repeaters help make your movements more predictable to surrounding traffic, which enhances overall road safety.
 

Are Side Repeaters Checked During an MOT Test?

Yes – during your MOT, the tester will carry out a thorough inspection of all your vehicle’s external lights, including the side repeaters.

They’ll check that these lights are secure, in good condition, and working correctly in line with your main indicators.

Can Damaged Car Side Repeaters Fail My MOT?

Yes – if your car’s side repeaters are not functioning properly at the time of the test, they can lead to an MOT failure.

The MOT includes a visual check to confirm that all external lights are working correctly and are clearly visible.

This includes indicator lamps and side repeaters, which are essential for signalling.

If a side repeater is cracked, missing, heavily faded, or doesn’t light up when the indicators are activated, it may be flagged as a major defect, particularly if it compromises the visibility of your indicators.
 

Reasons Your Side Repeaters Can Fail Your MOT

There are a few key reasons why a side repeater might result in a failed MOT test:

• Bulb failure or wiring issue: The most common fault. If the bulb has blown or there's a break in the wiring, the repeater won’t illuminate as required.
• Lens damage or fading: If the lens is cracked, obscured, or discoloured, it may reduce light output to the point where it’s not visible from the side.
• Incorrect flashing rate: MOT rules state that indicators must flash between 60 and 120 times per minute. Anything significantly outside that range – often caused by electrical faults or LED conversion errors – can be classed as a failure, but depending on the frequency of flashing, it may just lead to a minor defect.
• Not flashing in sync: If the side repeater is not flashing in unison with the main indicators, it may indicate an underlying electrical issue that needs fixing before the test.

Solutions for a Faulty Side Repeater

The fix will depend on the specific fault, but common solutions include:

• Replace the bulb: An inexpensive and straightforward solution if the repeater isn’t lighting up.
• Check wiring and connectors: Corroded or loose connectors can disrupt the electrical circuit. Your mechanic may clean or replace these components.
• Install a new lens or housing: If the repeater lens is damaged or cloudy, replacing it can restore visibility and compliance.
• Verify flashing synchronisation: If your indicators flash erratically or the repeater is out of sync, a technician may need to check the indicator relay or control module.

To avoid MOT failure, it’s worth carrying out a quick light check ahead of your test.

Simply turn on your indicators and walk around your car to make sure all repeaters and lamps are working and clearly visible.

Book Your MOT Online Through Blackcircles.com

At Blackcircles.com, we offer MOT and car servicing bookings across the UK, with a wide network of trusted garages, clear pricing, and convenient appointment times to suit your schedule.

Whether your MOT is due soon or your car needs a service, our seamless platform makes it easy to book an appointment in just a few clicks.

So when the time comes, make sure to book your MOT and service through the Blackcircles.com website!