TPMS Warning Light On? Here's What It Means

The Tyre Pressure Monitoring System (TPMS) light — a horseshoe shape with an exclamation mark — illuminates when one or more of your tyres is significantly under-inflated, typically around 25% below the recommended pressure. Since 2014, TPMS has been mandatory on all new cars sold in the EU and UK.

There are two types of TPMS. Direct TPMS uses pressure sensors inside each tyre that transmit real-time readings to the car's computer. Indirect TPMS uses the ABS wheel speed sensors to detect when one tyre is rotating faster than the others — a sign it has a smaller diameter due to low pressure. Direct systems are more accurate; indirect systems are more common on older vehicles.

Don't ignore a TPMS warning light. Pull over when it's safe to do so and visually inspect all four tyres. If one is obviously flat, you have a puncture that needs immediate attention. If all tyres look inflated, the pressure may be low enough to trigger the warning without being visibly flat.

Check the pressure in all four tyres at a petrol station or with a home gauge. Inflate any low tyres to the correct pressure for your vehicle (found in the owner's manual or door jamb sticker). Drive for a few minutes — on direct TPMS systems, the light should go out once pressures are correct. If it doesn't, a sensor may be faulty and need replacing.

Direct TPMS sensors contain batteries that typically last 7 to 10 years. When the battery dies, the sensor stops transmitting and you'll get a persistent TPMS warning even with correctly inflated tyres. Replacing a TPMS sensor requires removing the tyre from the wheel, which is a job for a professional tyre fitter.

TPMS sensors also need to be replaced or reprogrammed when you fit new tyres or rotate your tyres on some vehicle makes. Always ask your tyre fitter to check your TPMS sensors when having new tyres fitted.