# Tire Pressure Monitoring (TPMS) Service in Upland > TPMS light on or flashing? Route 66 Auto Repair in Upland tests each tire pressure sensor, replaces failed ones and runs the relearn your car needs. Source: https://route66autorepairshop.com/tire-services/tire-pressure-monitoring Updated: 2026-09-17 Business: Route 66 Auto Repair, 1775 W Foothill Blvd, Upland, CA 91786, (909) 608-7699 Hours: Monday to Friday 8 AM–5 PM, Saturday 8 AM–2 PM, Sunday closed **TLDR:** A **steady light** usually means low air; a **flashing light** means a system fault. We test every sensor and run the **relearn** your vehicle requires. The tire pressure monitoring system, or TPMS, warns you when a tire is low. When the light will not go off, or flashes at startup, Route 66 Auto Repair in Upland tests each sensor with a TPMS tool, reads its battery status and ID, and checks the actual pressures. Then we fix the real cause, whether that is air, a leak, a dead sensor or a relearn the car never received. ## Steady or flashing: what is the light telling you? - Steady light: at least one tire is well below its placard pressure. Check all four before driving far. - Flashing for about a minute, then steady: the system has a fault, such as a dead sensor battery or a sensor the car cannot hear. - Light on cold mornings, off by afternoon: pressures are borderline and drop with the temperature. - Light after new tires or a rotation elsewhere: a sensor may have been damaged, or a relearn was skipped. ## Direct and indirect TPMS Direct systems put a sensor inside each wheel, usually built into the valve stem. Each sensor has a small sealed battery that cannot be replaced, so the whole sensor is replaced when it dies. Indirect systems have no sensors in the wheels. They use the ABS wheel speed sensors to notice a tire spinning faster than the others, and they are reset from the dash or a menu after pressures are set. Heat is hard on sensor batteries and on the rubber seals of the valve, so Inland Empire summers age both. We check the sensor seal, nut and valve core any time a tire is off, which also prevents slow leaks. The [NHTSA tire safety pages](https://www.nhtsa.gov/equipment/tires) explain why a system like this is on your car. Two numbers explain most TPMS complaints. Under the federal rule these systems work to, the warning lamp is required to come on when a tire runs about 25 percent or more below the placard pressure, which is well past the point where handling and fuel economy have already suffered. Pressure also moves with temperature, roughly 1 psi for every 10 degrees F, which is why a cold morning on Foothill Blvd lights the dash. Set pressures cold to the placard on your door jamb, never to the maximum figure on the sidewall. ## Our TPMS service process 1. **Scan the sensors:** A TPMS tool wakes each sensor and reads its ID, pressure and battery status. 2. **Check real pressures:** We compare tool readings with a gauge and look for leaks on any low tire. 3. **Replace failed parts:** Dead sensors are replaced with parts matched to your vehicle, with new seals and cores. 4. **Relearn and verify:** We run the relearn procedure for your vehicle and confirm the light stays off on a drive. ## What's included - Sensor scan with ID and battery status - Gauge check and pressure set on all tires - Leak check on any tire reading low - Sensor seal, nut and valve core service when a tire is off - Relearn and a drive to confirm ## Need-now or need-later? **Need now:** - A steady light with a tire that is clearly low - A tire that needs air again within a day **Need later:** - A flashing light with all tires at correct pressure - A sensor battery reported as weak but still working ## How pricing and timing work A scan and relearn is a short job. Sensor replacement adds parts, and the tire must come off the wheel, so [tire mounting](https://route66autorepairshop.com/tire-services/tire-mounting) and [balancing](https://route66autorepairshop.com/tire-services/tire-balancing) labor appear on the estimate. If a slow leak turns up, the fix is covered on [tire repair](https://route66autorepairshop.com/tire-services/tire-repair). AAA members get 10% off parts and labor, up to $75. Many cars are done the same day when the board allows. ## Frequently asked questions ### Why does my TPMS light come back after a rotation? Some cars must relearn sensor positions after a rotation, and a sensor can fail when handled if its battery is weak. We test each sensor and complete the relearn before you leave. ### Should I replace all TPMS sensors at once? Not automatically. If the sensors are the same age and one battery has died, the others may follow, and doing them with new tires saves labor. We show you each battery reading so you can decide. ### Can I drive with the TPMS light on? Check your pressures first. If they are correct and the light is flashing, it is a fault you can book soon. If a tire is low, add air and have the cause found before a long drive. --- Call (909) 608-7699 or visit https://route66autorepairshop.com/contact for a written estimate.