Seeing the TPMS warning light on your dashboard usually means one or more tyres are under-inflated. But it can also mean the TPMS system itself has a fault - particularly if the light flashes, or won't clear after you've corrected tyre pressures.
This guide walks you through exactly what to check first, what you can safely do yourself, and when it's time to book a proper TPMS diagnostic - without wasting time or driving further than necessary on an unsafe tyre.
What Is TPMS - and Why Does It Matter?
TPMS (Tyre Pressure Monitoring System) is designed to alert you when tyre pressure drops below a safe threshold, helping you avoid poor handling, longer braking distances, and accelerated tyre wear.
Most modern vehicles use one of two system types.
Direct TPMS
- Pressure sensors fitted inside each wheel or on the valve
- Measures actual tyre pressure directly
- More precise - shows individual tyre readings
- Sensors contain batteries that wear out over time
Indirect TPMS
- Uses ABS wheel-speed data to detect pressure changes
- No physical sensors inside the wheels
- Less precise - detects rolling-radius changes
- Needs recalibration after pressure adjustments or tyre changes
TPMS has been mandatory on new passenger vehicles sold in the EU since November 2014, making it standard on most UK cars from around that time onwards.
Is It Safe to Keep Driving?
It depends on how the car feels and what you can see. In many cases a TPMS warning is a pressure issue you can address safely in minutes. In others, stopping promptly is the right call.
Even if the car feels normal, do not ignore the warning. Tyres can be significantly under-inflated and still look and feel broadly okay at low speeds.
What to Check First - 5-Minute Checklist
Before assuming the fault is sensor-related, run through these basics. Most TPMS warnings are resolved at this stage.
Work through these in order
- Check all four tyres visually - look for an obviously low tyre, a nail or screw in the tread, a sidewall bulge, or any visible damage.
- Check pressures cold - use a petrol station airline or a reliable gauge. Inflate to the vehicle placard pressure (found on the driver's door shut, fuel flap, or handbook) - not the maximum pressure shown on the tyre sidewall.
- Don't overlook the spare - some vehicles monitor the spare or a space-saver. If you've recently changed wheels or tyres, the system may need a reset or relearn.
- Re-check after 24 hours - if a tyre drops again, that's a strong sign of a slow puncture or a rim or valve leak requiring inspection.
- Consider the temperature - cold weather can lower tyre pressure enough to trigger the warning, especially overnight. Inflate to the correct pressure and it should clear after a short drive.
Steady Light vs Flashing Light
How the warning light behaves is one of the most useful clues about the underlying cause.
Steady (solid) warning light
- Most likely a pressure issue
- Inflate to the correct pressure
- Drive a short distance - many systems clear automatically
- If it doesn't clear, a manual reset may be needed
Flashing, then stays on
- Often indicates a system fault
- Sensor not communicating, dead battery, or incorrect sensor
- Still check tyre pressures first
- If pressure is correct, a diagnostic check is needed
How to Reset the TPMS Warning Light
Reset methods vary by make and model. Some vehicles clear the light automatically once pressures are corrected and the car has been driven for a short period. Others require a manual step.
Common reset routes include:
- TPMS reset button - often located in the glovebox or centre console; hold until the light blinks to confirm
- In-car menu reset - via infotainment or instrument cluster settings, typically under Tyre Pressure or Vehicle Settings
- Drive cycle reset - after inflating correctly, driving for a set period allows the system to relearn and clear the warning automatically
When It's Likely a TPMS Sensor Issue
If the warning light stays on or keeps returning after you've confirmed pressures are correct, the fault is most likely sensor-related. Common causes include:
Sensor battery failure
Most TPMS sensor batteries last 5-10 years. Once depleted, the sensor typically needs full replacement - the battery is not separately serviceable.
Valve stem damage or corrosion
Metal valve stems on direct TPMS sensors are prone to corrosion, particularly in areas with road salt. Damage during tyre fitting is also a common cause.
Loss of signal after tyre work
After tyre changes, wheel swaps, or sensor replacements, the sensor may need reprogramming and a relearn procedure to reconnect with the vehicle.
Incorrect sensor type fitted
Some vehicles require brand-specific or cloned sensors. Fitting a universal sensor without correct programming will leave the warning light on.
Indirect TPMS needs calibration
After pressure adjustments or tyre replacement, indirect TPMS systems require a calibration reset before they can monitor correctly again.
Diagnostics needed
When self-reset steps don't work, specialist equipment is required to read fault codes, identify the specific sensor, and carry out the correct repair.
TPMS and the MOT
For many UK vehicles, TPMS is included in the MOT inspection - so a warning light that's on due to a system malfunction is worth resolving before your MOT date.
- TPMS inspection applies to M1 vehicles first used on or after 1 January 2012
- A TPMS that is malfunctioning or obviously not working is categorised as a Major defect under the DVSA MOT inspection manual
- A Major defect means the vehicle will fail its MOT
Key points from this guide
- Always check tyre pressures first - most TPMS warnings are pressure-related and resolve once tyres are correctly inflated.
- A steady light most often means low pressure; a flashing light more commonly indicates a sensor or system fault.
- Cold weather can trigger the warning by lowering pressure below the threshold - inflating correctly usually clears it.
- If the light won't clear after pressures are correct, sensor diagnostics or reprogramming is likely needed.
- A malfunctioning TPMS is a Major defect at MOT for M1 vehicles registered from January 2012 onwards.
- A mobile TPMS technician can carry out diagnostics, sensor replacement, and programming at your location.