What does it mean?
C1503 is a Chassis (ABS, traction control, steering) fault code. It indicates: Tire Pressure Sensor 3 Internal .
Symptoms
- Tyre pressure warning lamp stays on after a start-up flash
- Third wheel position reports dashes or a value that never changes
- The system cannot complete a relearn or shows a sensor missing message
- Pressure adjustments to that tyre are not reflected on the display
- Vehicle handling and tyre condition are otherwise normal
Likely causes
- Internal sensor battery exhausted after long service, so transmissions stop
- Sensor cracked or its stem bent during a tyre change
- Corrosion at the valve stem seal letting water into the sensor body
- Impact damage from a pothole, kerb or road debris
- Sealant or excessive tyre balancing paste blocking the pressure inlet
- Aftermarket sensor that is not compatible with the vehicle protocol
- Sensor ID never registered after a wheel or sensor swap
How to fix it
- Read all sensor IDs, pressures and battery status with a TPMS tool
- Trigger each wheel sensor and note which one gives no response
- Check the actual tyre pressure with a gauge to rule out a genuine leak
- Compare the registered IDs in the module with the sensors physically fitted
- Inspect the valve stem, nut, seal and sensor body with the tyre dismounted
- Replace the failed sensor, program the ID and run the wheel position relearn
- Confirm all positions transmit correctly, then clear the code and road test