The TPMS warning is indicating a system fault rather than a low tyre. On cars first used from 2012 onwards this is a testable item, so a permanently lit TPMS light is a failure even when all four tyres are correctly inflated.
Wording as it commonly appears on an MOT certificate: “Tyre pressure monitoring system inoperative or warning indicating a system malfunction”.
What does it mean?
The TPMS warning is indicating a system fault rather than a low tyre. On cars first used from 2012 onwards this is a testable item, so a permanently lit TPMS light is a failure even when all four tyres are correctly inflated.
How serious is it?
Usually recorded as: Major. The tester assesses the actual vehicle on the day, so your certificate is what counts.
What normally causes it?
- A flat sensor battery — they're sealed units and typically last around seven to ten years
- A sensor damaged during a tyre change
- Sensors not relearned to the car after new wheels or a tyre rotation
- A corroded valve stem on an aluminium-stemmed sensor
What a mechanic would check
Read the TPMS system with a dedicated tool to see which sensor isn't reporting and whether it's transmitting at all. That immediately separates a dead sensor from a car that just needs a relearn — and a relearn costs a fraction of new sensors.
What might need replacing
- One TPMS sensor, or a full set if they're all of an age
- A relearn or reset procedure only
- Valve service kits when tyres are next changed
Can you still drive it?
It's a failure item on affected cars, but the light itself isn't a mechanical danger. The real cost is that you lose the early warning of a slow puncture, so check pressures manually until it's fixed.
More tyres and wheels failures · MOT failure decoder · Ask a mechanic about your certificate
This is general guidance from a UK mechanic, not a substitute for a physical inspection. Only the tester who inspected your vehicle can confirm what was recorded and why.