A lit TPMS icon reports a sensor reading — low pressure, a dying internal battery, or a communication fault — not necessarily a flat tire. Sacramento Tire Shop scans and resets sensors as part of every tire service, and replaces a sensor outright once its sealed battery has failed instead of resetting it over and over.
The TPMS light on the dash doesn't distinguish between a tire that's genuinely low and a sensor that's failing — both trip the same icon, and only a scan tells them apart. A steady light usually points to pressure; a light that flashes for a stretch after startup and then goes solid usually means the system found a fault, most often a sensor battery near the end of its life.
Sensors get scanned and reset as part of every tire change and inspection, and when the sensor itself has failed — not the tire, the sensor — it gets replaced rather than reset again and again.
Why does a shop replace the whole sensor instead of just fixing the tire?
The battery that powers a TPMS sensor is sealed inside the housing; there's no way to open it, swap the cell, and reseal it to the same standard. When that battery runs down, the fix is a new sensor, not a repair to the old one. It wears out on a schedule of its own, independent of how the tires themselves are holding up.
Does a new set of tires always mean new sensors?
Not automatically. If the sensors are reading correctly and their batteries still have life in them, they get remounted into the new tires rather than swapped for no reason. They only come out when a scan shows one isn't reporting, or isn't reporting reliably — a new tire doesn't change what the sensor inside it is doing.
Why won't the TPMS light turn off after I've filled my tires to the right pressure?
If the light stays on after all four tires are confirmed at the correct pressure, the sensor itself is the likely problem — either its reading is off or it's stopped reporting. It needs a scan, not another round of air.
Is a flashing TPMS light different from a solid one?
Yes. A solid light is almost always a pressure reading; a light that flashes for roughly a minute after the car starts and then goes solid is the system reporting a fault in the sensor itself, not the tire pressure.
Can the TPMS light be reset without replacing anything?
If a sensor is reading correctly and just needs to relearn its position after a tire rotation or new install, yes — that's a reset, not a replacement. It only becomes a parts job when the sensor has actually stopped working.