Why Is My Tire Pressure Light On?
- Tyler Ellis
- Oct 15
- 3 min read
When the dashboard TPMS (tire pressure monitoring system) lamp pops on, it’s your car warning that at least one tire is outside its safe pressure range. Sometimes it’s a small temperature swing; other times it’s a puncture that needs immediate attention. If you’re asking, “Why Is My Tire Pressure Light On?”, the key is to verify actual pressures quickly and find out why they changed.
At Round Rock Auto Center, we pinpoint leaks, set pressures to spec, and check alignment so your tires wear evenly and you drive with confidence.
Why Is My Tire Pressure Light On? Common Causes & Quick Checks
The TPMS compares pressures to programmed targets. When readings drop (or, less commonly, spike), the lamp turns on. Typical triggers:
Seasonal temperature swings – Pressure changes about 1 PSI for every 10°F. A cool morning can nudge a borderline tire below spec.
Slow leaks – Nail/screw punctures, bead leaks, or a hairline crack in the wheel can drop pressure a little each day.
Aging valve stems/TPMS seals – Rubber stems and sensor O-rings dry out and seep air.
Impact damage – Potholes and curbs can bend rims or bruise sidewalls, causing a sudden or delayed leak.
Incorrect fill – After service or a gas-station top-off, tires may be set unevenly or below the door-jamb spec.
TPMS sensor battery failure – The internal battery (often ~7–10 years) dies and the system can’t read pressure reliably.
Fast checks right now:
Use a quality gauge and compare each tire to the door-jamb placard (not the sidewall max).
Inspect tread and sidewalls for nails, cuts, bubbles, or wet/greasy spots.
Don’t forget the spare—some vehicles monitor it too.
What Causes This Problem? (Diagnostic Clues You Can Use)
Light on at dawn, off by afternoon → Temperature-related drop; you’re near the threshold.
One tire consistently low → Slow puncture, bead leak, or valve issue on that corner.
Light flashes for a minute, then stays on → Often a sensor/battery fault or communication issue.
After a pothole hit → Possible rim bend or sidewall bruise; inspect ASAP.
All tires low after weather change → Set all four to spec; recheck in a week.
If Why Is My Tire Pressure Light On? keeps appearing even after you set pressures correctly, you likely have a leak or a weak TPMS sensor.
How to Fix It? (Step-by-Step)
DIY steps:
Set pressures cold to the door-jamb spec (usually measured after the car sits a few hours).
Recheck in 24–48 hours. A 1–2 PSI drop suggests a slow leak; larger drops need immediate attention.
Inspect/rotate valve caps and look for hissing; replace damaged valve cores/caps.
Mark and monitor a suspected tire with chalk at the valve position so you can see if the leak rate changes.
What we do at the shop:
Water dunk or leak-seek to find tiny punctures, bead leaks, and porous wheels.
Patch/plug from the inside (when safe and in the repairable zone) or recommend replacement for sidewall/belt injuries.
Bead reseal and rim repair for minor bends/corrosion.
TPMS testing & programming to replace weak sensors and sync them to your vehicle.
Alignment & tread inspection to prevent uneven wear that can invite future leaks.
Set all four to spec and road-test to confirm the lamp stays off.
Prefer a quick, done-right solution? Book a tire/TPMS service at Round Rock Auto Center.
How to Fix It? (When the Light Won’t Reset)
Drive cycle reset: Many cars clear the lamp after a few miles once pressures are corrected.
Manual reset: Some models have a TPMS reset or “set” button; follow the owner’s manual steps.
Sensor learning: After tire rotation or sensor replacement, we perform a relearn so each wheel’s ID matches its location.
Scan-tool diagnosis: If the light flashes before staying on, we scan the TPMS module for sensor battery or communication faults.
Why Act Now
Safety: Underinflated tires overheat, increasing blowout risk—especially at highway speeds.
Tire life & fuel economy: Just 5 PSI low can shave thousands of miles off tread life and cut MPG.
Braking & handling: Low pressure lengthens stopping distance and dulls steering response.
Avoid hidden damage: Driving on a soft tire can pinch the sidewall or bend a rim, turning a repair into a replacement.
Still wondering Why Is My Tire Pressure Light On? If pressure keeps dropping or the lamp flashes, it’s time for a professional inspection.
Schedule a TPMS & Tire Check
Get rid of the dash lamp and get your tires back to spec. Contact Round Rock Auto Center to schedule a TPMS diagnostic and tire inspection. We’ll find the leak (or failed sensor), fix it right, and set pressures so you can drive confidently in any weather.
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