Will a TPMS Warning Light Cause an MOT Failure?
Yes. If your tyre pressure monitoring system (TPMS) warning light stays illuminated while the engine is running, your car will fail its MOT.
Many drivers assume a tyre pressure warning light is minor and won’t affect the test. However, because TPMS is a safety feature designed to alert the driver to tyre pressure issues, a warning light indicating a fault is enough for the vehicle to fail.
What Is a TPMS Warning Light?
TPMS stands for Tyre Pressure Monitoring System. It monitors the air pressure in your tyres and alerts you if one or more tyres fall below the recommended level.
The warning usually appears as a symbol that looks like a tyre with an exclamation mark inside it.
If the light comes on, it means the vehicle has detected either low tyre pressure or a potential fault within the monitoring system.
Why TPMS Is Checked During an MOT?
Tyre pressure plays an important role in vehicle safety. Incorrect tyre pressure can affect braking performance, handling, tyre wear and fuel efficiency.
For this reason, TPMS became part of the MOT inspection in 2015 for vehicles first registered on or after 1 January 2012.
During the MOT, the tester checks that the TPMS warning light functions correctly and that it does not remain illuminated once the engine is running.
If the system indicates a fault and the light stays on, the vehicle will fail the test.
What Does a TPMS Warning Light Usually Mean?
A TPMS warning light does not always mean there is a major fault.
In many cases, it simply means that one or more tyres are below the recommended pressure. However, it can also indicate an issue with the TPMS system itself.
Common causes include low tyre pressure, a faulty TPMS sensor inside the wheel, a damaged valve or a system fault.
Regardless of the cause, the warning light must not remain illuminated for the vehicle to pass its MOT.
What Should You Do If Your TPMS Warning Light Comes On?
If your TPMS warning light appears, the first step is to check your tyre pressures yourself.
Most fuel stations have tyre inflation machines where you can check and adjust the pressure in each tyre. The recommended tyre pressures for your vehicle are usually listed on a sticker inside the driver’s door frame, and sometimes inside the fuel flap.
Check each tyre and adjust them to the correct pressure. Once all tyres have been set properly, reset the TPMS warning light using the vehicle’s system. In many cases, this alone resolves the issue.
Tyre pressures can change with the weather. Colder temperatures can cause the air inside tyres to contract, which may trigger the warning light even when there is no underlying problem.
While checking the tyres, it is worth noting if one tyre is significantly lower than the others. This can indicate a slow loss of pressure.
After adjusting the tyres to the correct pressure, monitor them over the next few days. If the warning light returns, check the pressures again to identify which tyre may be losing air.
A gradual loss of pressure could be caused by:
- a small puncture
- a leak around the wheel rim
- a faulty valve
In some cases, the issue may be related to the TPMS sensor itself, rather than the tyre.
What If the TPMS Light Comes On Then Goes Off?
It is normal for most dashboard warning lights to briefly illuminate when the ignition is switched on.
If the TPMS light comes on during start-up and then goes out once the engine is running, this shows the system has completed its self-check and is operating correctly.
If the light remains illuminated while the engine is running, the vehicle will fail its MOT.
