A P0501 is a code for a right front (passenger side) wheel speed sensor circuit fault. As I stated in the earlier post there is no way to tell if it is the sensor, the wiring or even a fault internal to the PCM itself without physically testing the circuit and sensor. Codes don't work like that. All they tell you is that the computer sees an issue in one part of the system. In this case it is a circuit code for the right front. That could mean the coil in the sensor failed to open, the wiring from the sensor to the PCM has broken, there is corrosion in the harness connection or the PCM has an internal failure and cannot read the signal. A good shop would do the testing I showed to narrow down the fault and replace only the needed part. Many other shops, however, will simply replace the speed sensor, then see if the fault went away, if it did they guessed right, if it didn't, they would replace part of the harness and try again, still not repaired? Replace the rest of the harness. Light is out? Well, they finally got there, but the customer pays for it in labor and parts that may not be needed.
That is why my motto is "Test don't guess" In this case simply testing for the speed sensor sine wave at the PCM with an oscilloscope would test the sensor and harness fully, but even a simple continuity test at the PCM pins to the sensor would narrow it down. Say you test it and it shows an open circuit, then you short the connector where the sensor plugs in and it shows a connection, the sensor is likely the issue.
Wednesday, March 26th, 2025 AT 7:36 PM
