A customer reports that the low tire pressure warning light (TPMS) on their vehicle remains illuminated after having new tires installed. The technician verifies all tires are inflated to the correct pressure. A scan tool shows that one wheel speed sensor is not reporting tire pressure data, but is reporting wheel speed data correctly. What is the most likely cause?
- AAn open circuit in the TPMS antenna wiring.
- BIncorrect TPMS sensor relearn procedure.
- CA faulty wheel speed sensor.
- DA dead battery in the TPMS sensor.
Show answer & explanationAnswer & explanation
Correct answer: D. A dead battery in the TPMS sensor.
Modern TPMS sensors are often integrated with the valve stem and contain a battery to power their pressure transmitting function. If a sensor is reporting wheel speed (which some TPMS systems infer from wheel rotation, not directly from the TPMS sensor itself), but not transmitting pressure data, it strongly suggests the TPMS sensor's internal battery has died, preventing it from broadcasting its pressure information.
Why the other options are wrong
- A. An open circuit in the TPMS antenna wiring would prevent reception from all sensors in its range, not just one specific sensor failing to transmit pressure data while other functions are implied to be working.
- B. An incorrect relearn procedure might prevent the system from recognizing the sensor, but it wouldn't necessarily cause the sensor to stop transmitting data due to a dead battery.
- C. A faulty wheel speed sensor would likely affect ABS/traction control and not report wheel speed correctly, which is not the case here.
TPMS Sensor Dead Battery
A TPMS sensor that fails to report tire pressure data, despite correct tire inflation and potentially correct wheel speed data (from other sensors), often indicates a dead internal battery within the TPMS sensor.
- TPMS sensors have finite battery life (5-10 years).
- Battery powers pressure transmission.
- Wheel speed data can come from ABS sensors, not necessarily TPMS.
Memory trick: TPMS light's on, no pressure data: The 'BATTERY' is 'DEAD', not just 'TIRED'.