ASE A4 Suspension and SteeringWheels and Tires Diagnosis and RepairMedium
A technician is diagnosing a TPMS light that illuminates intermittently. They connect a scan tool and retrieve a DTC indicating 'Low Tire Pressure, Right Rear'. After checking the tire pressure and confirming it is correct, the technician performs a TPMS sensor activation and relearn procedure. The relearn procedure fails repeatedly for only the right rear sensor. What is the MOST likely cause of the repeated relearn failure?
- ACorroded valve stem cap
- BUnderinflated spare tire
- CFaulty TPMS sensor battery in the right rear wheel
- DIncorrect tire rotation pattern
Show answer & explanationAnswer & explanation
Correct answer: C. Faulty TPMS sensor battery in the right rear wheel
If a TPMS sensor's battery is dead or weak, it will not be able to transmit its signal to the vehicle's receiver, preventing it from being activated or learned into the system, even if the tire pressure is correct.
Why the other options are wrong
- A. A corroded valve stem cap would not affect the internal TPMS sensor's ability to transmit its signal.
- B. An underinflated spare tire would typically not prevent a specific road wheel sensor from relearning, unless it's part of a full-size spare TPMS system and the issue is with the spare itself.
- D. An incorrect tire rotation pattern might confuse the vehicle's system if it uses an auto-locate feature, but it wouldn't prevent an individual sensor from being relearned if it's functional.
TPMS Sensor Battery Failure
TPMS sensors are battery-powered, and a dead or weak battery will prevent the sensor from transmitting data, leading to relearn failures and a persistent warning light.
- Batteries are typically non-replaceable within the sensor unit.
- Expected lifespan is 5-10 years.
- Often signaled by intermittent warnings before complete failure.
Memory trick: Sensor Needs Power to Talk.