What the TPMS light means and what you need to do

Under U.S. law, the TPMS is required to warn the driver of cars and light trucks when tire pressure is 25 percent above or below the recommended pressure for that vehicle. That pressure value varies from vehicle to vehicle and is listed in the car manual or on a sticker on the driver’s door post.

If you have aired up your tires to the correct pressure but the TPMS is still on, try driving your car at 50 miles per hour for around 10 minutes. Stop the car, turn it off, and when you start it up again the TPMS should be reset and the light off. If this doesn’t work, check your vehicle’s manual for instructions on how to reset the TPMS system, or consult a tire professional.

The TPMS exists for safety reasons, so when it indicates a problem, you should heed it and check your tires’ pressure. If you check the pressure of your tires (including your spare if it has a TPMS sensor) when they are cold (it’s been three or more hours since they were driven on) and they are all at the recommended PSI, this may mean your TPMS is not functioning properly. If this is the case, it may be safe to drive on them, but you should fix the issue as soon as possible or contact a tire service professional. It is important to have a properly functioning TPMS so you can be alerted if your tire pressure falls outside of the correct range.

Essentially, TPMS is a warning system that alerts you when your tire is 25 percent above or below the recommended pressure. Low tire pressure is one of the mechanical conditions it warns you about. Your tires can be overinflated or underinflated without setting off the warning system, so it is important to check your tire pressure monthly and before long trips. When the TPMS signal lights up on your dashboard, this means your tire pressure is 25 percent above or below the recommended pressure.

Temperatures changes can influence tire pressure, as hotter air expands and colder air contracts. If one or more of your tires is close to the minimum or maximum threshold for triggering the warning, temperature fluctuations caused by seasonal or daily changes or the heat generated by driving on a tire can be enough to briefly activate the warning light. To address the issue, check all of the tires when cold and adjust the pressure to the recommended value. This should bring the pressure values close enough to the recommended ones that temperature swings will no longer be enough to set off the TPMS.

If the TPMS light flashes when you start up the car and then stays on, this usually means one of your TPMS sensors has gone bad. In this situation, you should bring your car into an auto repair shop as soon as possible to have the problem fixed.

A TPMS is designed to alert you to serious problems with your tire pressure that can cause tire damage, difficulty controlling the vehicle, accidents, or accelerated tire wear. But it’s still important to do regular air pressure checks, because your tires can still be moderately underinflated or overinflated even if the TPMS light doesn’t come on. Moderate deviations in tire pressure can cause damage to your tire, impact your gas mileage and the life of your tread, and diminish your vehicle’s braking, cornering, and handling abilities.

You should always try to keep your tires inflated to the pressure recommended by your vehicle manufacturer. When tires are operated at improper pressures, the tire’s sidewalls can flex and damage the belting structure in the tires. You will not be able to see this damage, which can increase over time. This is why you should maintain proper inflation pressure and try to avoid driving when the TPMS light is on. If you absolutely must drive a short distance on a tire with severely low pressure, drive very slowly and use extreme caution. The tire should be inflated or changed before driving anywhere.

If you still have questions about your tire pressure or you need to fix a tire, get help from your nearest tire dealer so you can stay safe on the road.