TPMS Tire Pressure Warning Light On
The TPMS (Tire Pressure Monitoring System) light, usually a horseshoe shape with an exclamation point, means at least one tire is significantly under-inflated, typically 25% or more below the recommended pressure. The most common harmless cause is a temperature drop, since tires lose about 1 PSI for every 10-degree fall in temperature. It's usually a quick fix, but a low tire affects handling, braking, and fuel economy, so don't ignore it.
Trouble codes you may see
If you scan the car, these are the OBD-II codes most often behind this symptom:
Common causes
- 1
One or more tires low on air
The intended trigger. A slow leak, a nail, or just normal pressure loss over time drops a tire below the threshold. Inflate all tires to the door-jamb spec and the light should reset.
- 2
Cold weather temperature drop
A sharp drop in outside temperature lowers tire pressure and can trip the light overnight. It often resets after the tires warm up or you add a few PSI.
- 3
Slow leak or puncture
A nail, screw, or a leaky valve stem lets pressure bleed down so the light keeps returning after you re-inflate. Check for embedded objects and have leaks repaired.
- 4
Faulty TPMS sensor
Sensors have batteries that die after 5-10 years. A dead or failing sensor sets a communication code (C0750-C0770) and a steady or flashing light even with proper pressure.
- 5
Recent tire service without TPMS relearn
After rotation, replacement, or a new sensor, the system may need to be relearned/reset so it reads the correct positions.
- 6
Spare or mismatched tire in use
Mounting a spare without a sensor, or a tire the system doesn't recognize, can keep the light on.
What to do
Check and adjust all four tires to the pressure on the driver's door jamb label (do it when tires are cold for an accurate reading); the light usually clears within a short drive. If the light comes right back, you likely have a slow leak or puncture, inspect for nails and have it repaired. A TPMS light that flashes for about 90 seconds at startup and then stays on points to a sensor fault that a shop should diagnose.
Not sure it's your car?
Snap a photo or describe what you're seeing and let Au7o confirm the likely cause for your exact year, make, and model — free.
Diagnose my car free