Why Is My Tire Pressure Light On But Tires Seem Fine?
A lit TPMS light does not always mean a flat tire. Here are the most common causes and how to fix each one.
Do Not Ignore the TPMS Light
Even if your tires look fine visually, a TPMS warning should be taken seriously. Tires can lose significant pressure and still look "normal" to the eye. A tire that looks 90% inflated may actually be 20% below the recommended pressure.
Most Common Causes
1. Cold Weather (Most Common)
Tire pressure drops roughly 1–2 PSI for every 10°F decrease in temperature. A car sitting outside on a cold night commonly triggers the TPMS light. The light may go off once the tires warm up from driving — but the underlying pressure is still low and should be corrected.
Fix: Inflate all four tires to the spec on your door jamb sticker.
2. Slow Leak (Nail, Screw, or Damaged Valve)
A small nail or screw can cause a very slow leak — losing 1–2 PSI per day. You may not notice visually for days. Check each tire with a gauge and look for embedded objects.
Fix: Visit a tire shop for a plug or patch. Most repairs cost $15–30 and take under 30 minutes.
3. Faulty or Dead TPMS Sensor
Each wheel has a battery-powered TPMS sensor inside. These batteries last 5–10 years and cannot be replaced separately — the entire sensor must be replaced. A dead sensor may trigger the TPMS light even with correct pressure.
Indicator: The light blinks rapidly for 60–90 seconds after startup (varies by vehicle) before staying solid — often indicates a sensor fault rather than a pressure problem.
Fix: Sensor replacement at a tire shop; cost is typically $50–100 per sensor.
4. Pressure Not Restored After Inflation
Some vehicles require a manual reset after refilling tires. The TPMS does not always update automatically until you drive 10–20 minutes.
Fix: Drive for 10–20 minutes above 25 mph. Some vehicles have a TPMS reset button (check your manual).
5. Spare Tire Sensor (If Equipped)
If your vehicle monitors the spare tire pressure, a low spare can trigger the TPMS light even when all four regular tires are fine.
TPMS Trigger Threshold
By law (FMVSS 138), the TPMS must warn you when any tire is 25% below the recommended pressure. For a tire with a 36 PSI spec, the light triggers at approximately 27 PSI.
Frequently Asked Questions
Can I drive with the TPMS light on?
Check and correct tire pressure before driving any significant distance. A tire that triggered TPMS is at least 25% underinflated, which increases heat, wear, and blowout risk. It takes 5 minutes to check and fill.
My TPMS light goes on every winter and off every spring. Is my car OK?
Yes, this is normal. Seasonal temperature swings cause pressure changes that cross the TPMS threshold. Simply refill your tires to spec each fall when temperatures drop consistently.
How much does it cost to replace a TPMS sensor?
Typically $50–100 per sensor including labor, or $150–300 for all four. Prices vary by vehicle make and sensor type. Some shops replace sensors when you buy new tires; it's a good time to do it.
Does the TPMS light mean I have a flat tire?
Not necessarily a flat — just that pressure is 25% below spec. Check all four tires with a gauge. If one is significantly lower than the others, you likely have a slow leak or puncture.