What is a TPMS fault?
A TPMS fault is a problem with a vehicle’s Tire Pressure Monitoring System that prevents it from accurately reporting tire pressures or from properly triggering the warning light when pressures are out of spec.
This article explains what TPMS is, why faults occur, how to diagnose and fix them, and how to stay safe on the road. It covers the differences between direct and indirect TPMS, common failure causes, practical steps to take when a fault appears, and tips for prevention.
Understanding TPMS and how it works
There are two main approaches to tire pressure monitoring. Knowing the difference helps explain why faults occur and how they are diagnosed.
Direct TPMS vs Indirect TPMS
Direct TPMS uses in-wheel sensors with batteries to measure each tire’s actual air pressure and transmits the data to a central control unit. Indirect TPMS uses data from the vehicle’s existing wheel speed sensors (part of the ABS/ESP system) to infer underinflation by comparing rotational differences between tires. The following list highlights key distinctions.
- Direct TPMS provides actual tire pressure readings for each wheel and typically requires sensor replacement if a battery dies.
- Indirect TPMS does not measure pressure with a sensor in the tire; it flags potential underinflation based on wheel speed data and system calibration.
- Direct systems usually require a relearn or reset after tire changes or sensor service, while indirect systems rely on calibration through driving and ABS data.
- Direct TPMS can warn about low pressure even if a spare tire is in use (depending on the system), while indirect systems depend on the overall wheel data from the ABS/ESP network.
In practice, most newer vehicles use direct TPMS, but some models still rely on indirect methods, especially in markets or trims where sensor cost is a consideration.
Common causes of a TPMS fault
Several issues can trigger a TPMS fault or cause the warning light to stay on. The following list covers the most frequent culprits.
- Dead or weak TPMS sensor batteries inside one or more wheels.
- Damaged, corroded, leaking, or otherwise faulty TPMS sensors or valve stems.
- Recent tire or wheel changes without performing the required TPMS relearn/reset procedure.
- Faulty TPMS control module, receiver, or related wiring and connectors.
- ABS/ESP or wheel-speed sensor faults that affect indirect TPMS readings.
- Extreme temperatures or rapid pressure changes that temporarily confuse the system.
If any of these conditions are present, the TPMS warning may illuminate or stay on until the issue is addressed. A persistent fault often requires diagnostic testing and potential sensor replacement or system reprogramming.
What to do when you see a TPMS fault
When a TPMS fault appears, follow a practical sequence to determine whether the issue is a simple pressure check or a more complex system problem.
- Check all tires with a reliable gauge and inflate to the vehicle’s recommended pressure (found on the door jamb sticker or owner’s manual).
- Inspect tires for damage, punctures, or slow leaks that could be causing false alerts.
- If pressures are correct, perform the vehicle’s TPMS relearn/reset procedure as described in the owner’s manual or by the dealer.
- If the light remains after a relearn, use a diagnostic tool or visit a shop to read TPMS codes and verify sensor status.
- Replace faulty sensors or the TPMS control module as recommended by a qualified technician. Sensor batteries typically have a finite lifespan.
Conclusion: A systematic check—from tire pressures to relearn procedures and diagnostic codes—helps determine whether the fault is temporary or requires professional repair.
Maintenance and prevention
Preventing TPMS faults involves careful maintenance and timely sensor care. The following practices reduce the likelihood of faults and improve reliability.
- Regularly check tire pressures and keep them at the recommended levels, especially with seasonal temperature changes.
- When changing tires or wheels, perform the TPMS relearn or reset as required by the vehicle.
- Monitor for signs of sensor damage, corrosion at valve stems, or tire bead issues, and replace compromised components promptly.
- If you notice frequent false warnings, have the TPMS sensors and wiring inspected for faults, and consider sensor battery replacement when appropriate.
- Keep ABS/ESP systems in good health, since indirect TPMS relies on clean signals from wheel-speed sensors.
Conclusion: Proactive tire maintenance, proper relearn procedures after service, and timely sensor replacement help maintain a reliable TPMS and reduce fault occurrences.
Symptoms, safety implications, and when to seek help
Beyond a fault code or warning light, consider these practical implications and safety tips to avoid compromising road safety.
- The TPMS warning light may indicate underinflated tires, which increases wear, reduces fuel efficiency, and can affect handling and braking.
- A persistent TPMS fault without obvious tire pressure issues should be diagnosed to prevent driving with undetected underinflation or worn tires.
- Professional inspection is recommended if you cannot identify the cause or if multiple wheels show sensor problems.
Summary: Treat a TPMS fault as a warning worth investigating. Start with basic tire pressures, proceed to relearn/reset if applicable, and consult a technician for sensor or module diagnostics as needed.
Summary
A TPMS fault indicates a problem with the Tire Pressure Monitoring System, which can stem from sensor or wiring issues, a failed control module, wheel changes without relearn, or simple underinflation. By verifying tire pressures, performing relearns, reading diagnostic codes, and replacing faulty sensors when necessary, most TPMS faults can be resolved. Regular maintenance and attention to the system help keep both tire health and vehicle safety at the forefront.
