A steady TPMS light means at least one tire is meaningfully low on air; a blinking one usually means a sensor fault, not a tire problem. San Diego Tire Shop reads the actual pressure and sensor ID off each wheel with a scan tool rather than guessing from the dash, because the two lights call for two different fixes.
Most TPMS confusion comes down to not knowing which of the two lights you're looking at. A light that comes on steady and stays on is the sensor doing its job — a tire's actually low and needs air or a look for the cause. A light that blinks for a set stretch after startup and then stays on solid is the system telling you it can't read one or more sensors at all, which is a battery or communication problem, not a tire.
The battery inside a TPMS sensor is sealed in and isn't replaceable on its own — once it's dead, or close to it, the whole sensor gets swapped. Corrosion on the valve stem base is the other common failure, especially on wheels that don't get cleaned around the valve during a routine tire service. We'd rather tell you nothing's wrong than replace a sensor that's fine, which is a chunk of why the shop holds a 5.0 rating across 39 reviews on Google.
Why does the TPMS light come back on right after a tire swap?
Every sensor broadcasts its own ID to the vehicle's receiver, and most vehicles need to be told the position of each one again — a relearn — any time a wheel comes off and goes back on somewhere else, or a sensor gets replaced. Skip the relearn and the light stays on even though every sensor is working fine, because the car's still looking for the ID it memorized before.
Can I just ignore the light if the tires look fine?
You can, for a while — a slow leak or a temperature-related pressure drop won't destroy a tire in a day. But a tire can look essentially normal to the eye long after it's meaningfully underinflated, and running low is a common reason tires wear unevenly or run hot on a long freeway stretch. The light is more reliable than the eyeball test, which is exactly why the sensor's there.
- Light comes on in cold weather and clears once the tires warm up on the freeway — check pressure, likely just seasonal
- Light stays on regardless of temperature or driving, and the gauge reads fine — likely the sensor itself
Do I need a relearn every time I rotate my tires?
Most vehicles do, since rotating changes which sensor sits in which position and the car needs to be told that. Some newer systems relearn automatically after a few minutes of driving; older ones need the procedure done with a tool before the light clears.
How long do TPMS sensor batteries last?
There's no fixed mileage — it depends more on how many years the sensor's been in service than how many miles are on the tires, since the battery drains the whole time the wheel's on the car, not just while driving. When one goes, it's usually one at a time, not all four together.
Can you fix a TPMS light without replacing the sensor?
Sometimes. If the light's on because of a real pressure difference, correcting the air solves it with no parts needed. If a sensor's not communicating at all, it usually needs replacing rather than repairing, since the battery inside isn't serviceable on its own.
Can I get this looked at without an appointment?
Usually, yes — TPMS checks are typically a walk-in job. We're open Mon–Fri 8:00 AM – 5:00 PM, Sat 8:00 AM – 2:00 PM, closed Sun, and it's normally quick enough to wait for.