Why is my Tire Pressure Monitoring System (TPMS) light coming on? Here’s Why

By Greg Burchette

If your TPMS (tire pressure monitoring system) warning light goes on during a cold snap, it may not mean your tire has a leak.

Tire pressure can decrease about 1 PSI (pound per square inch) for every 10 degrees the temperature drops. It’s not that more air is escaping your tires, but rather the air inside the tire condenses, taking up less space when it’s cold. It’s similar to how a cake, just out of the oven, flattens out a bit as it cools.

Tires also lose about 1 PSI per month just from seepage of air around the edge of the rim and through the tread itself.

These two factors combined can cause the air pressure in a tire to go 25 percent below the recommended fill pressure. This is what triggers the sensing transmitters inside your tires to illuminate your TPMS dash light. Whenever your TPMS light comes on, have your air checked and bring your tires up to the proper pressure.

Winter Tire Pressure

Temperature changes outside affect your tire pressure. If it gets up to 45 degrees by day and drops to 15 degrees at night, your tire pressure will vary 3 PSI, not counting normal air loss. This is why it’s not unusual to have the low-pressure indicator light go on first thing in the morning, since it’s usually coldest overnight.

The light may shut off on its own after you drive 20 minutes or so, as the air in your tires warms and expands and proper inflation level stabilizes.

Regardless, you should get your air checked right away. The TPMS light means your tires are at least 25 percent below the proper air pressure. This is a safety risk, especially if you’re carrying a load close to your vehicle’s max capacity. There’s a greater chance of tire failure, compromised handling and increased wear and tear on your tires. Your engine has to work harder to keep speed and our gas mileage will go down.

When you top off your tires, the TPMS light will go off as the tire regains the proper pressure.

Note: If the warning light is flashing, this is a problem with the vehicle’s TPMS system, not your tires, and you should have your car looked at..

One More Reason Your TPMS Light May Go On

Your TPMS light may flash if your vehicle’s onboard computer can’t detect the sensor because you’re using a spare tire. They typically don’t have TPMS sensors.

How to Get Winter Tire Pressure Right

Once a month, have your pressure checked when the tires are cold (meaning the car is parked outside and hasn’t been driven in four hours) and inflate them to what’s indicated on your placard located on the inside of your car door.

If you have any questions about TPMS please do not hesitate to call us at Bridgewater Motorworks at 908.218.9100.

www.bwmotorworks.com