Tire pressure light

Tire pressure light

Check your tire pressures as soon as you can, ideally today, but you do not need to pull over right now to do it. Drive normally to a gas station or your driveway if you have a gauge at home.

What the light means

This is the tire pressure monitoring system, TPMS for short. Each wheel has a small sensor that reads air pressure and reports it back to the car. The amber horseshoe with the exclamation mark means at least one tire is reading lower than the pressure set for your car by the manufacturer. It is not measuring tread or tire age, only air pressure.

Common causes

Most of the time this means exactly what it says: one tire has lost air, usually from a slow leak, a small puncture, or a nail. Check that tire first for anything obvious stuck in it.

The other very common cause is temperature. Air contracts as it cools, so the first cold morning of the season can drop every tire by a few psi at once and light up the warning even though nothing is actually wrong. If the light came on after a cold night and all four tires read a little low but close to each other, that is probably all this is. Top them up to the number on the sticker inside the driver's door and the light should go off after a short drive, sometimes not immediately.

Less often, the sensor itself is failing rather than the tire losing air. TPMS sensors run on small batteries that do eventually die, usually after several years. If pressures check out fine on all four tires and the light stays on, or comes back on right away, that points to a sensor problem rather than a tire problem.

What it takes to put right

If it is just low air, filling the tire to the correct pressure fixes it. If a tire keeps losing air over days or weeks, it has a leak somewhere and needs to come off the wheel to be checked, patched if possible, or replaced if the damage is in the sidewall or otherwise not repairable. If it turns out to be the sensor, that gets diagnosed and replaced separately from the tire itself. We can check all of this at Auto Star, pressures, the tire itself, and the sensors, and tell you which one it actually is rather than guessing.

Warning-light symbols and meanings vary by vehicle — always check your owner’s manual. This is general guidance based on what the light indicates, not a physical inspection, and a light on its own never names a failed part.