Why the tyre-pressure warning light comes on

The TPMS warning light comes on when the system detects pressure outside its threshold or a fault, but it does not by itself tell you which tyre is affected. Slow down and stop somewhere safe, check the wheels and use the figures in the handbook.

Distinguish a warning from an emergency

A steady warning may mean that one or more tyres have lost pressure; a flashing light or a different message may refer to a sensor or the system. The exact meaning varies by make and model, so check the TPMS section of the handbook rather than guessing from the symbol alone.

Slow down gradually and find somewhere safe to stop, away from traffic. Look at all the wheels: do not drive on a tyre that is visibly flat, misshapen or damaged. Do not inspect a tyre while in a traffic lane or on a narrow hard shoulder exposed to traffic.

Check pressure and possible damage

With the vehicle stopped, measure each tyre with a pressure gauge, ideally when cold, and compare it with the label or handbook. If you find a puncture, bulge or rapid pressure loss, call for assistance. Use a repair kit or spare wheel only as instructed by the manufacturer.

If all the tyres look intact but the pressure is low, adjust it according to the vehicle table and check whether it drops again. Temperature changes can affect the reading, but do not assume a leak is due to cold weather without checking. If the warning persists, have a garage inspect the sensors and system.

Reset the warning only after checking

Some cars need a reset or recalibration after tyre pressure is adjusted; others update automatically. Follow the handbook and do not clear the warning before checking the cause, or you may remove the reminder without fixing a leak.

After adjustment, check the pressure again over the following days and watch for uneven wear or air loss from a wheel. If the warning returns, do not keep resetting it: arrange a technical inspection. A TPMS warning is helpful, but it does not replace regular inspection and correct tyre maintenance.

Quiz Patente Ufficiale offers chapters, exam quizzes and review of mistakes so you can revise while arranging a garage inspection.