The P0502 trouble code indicates that the vehicle speed sensor (VSS) “A” is reporting a low input signal to the engine control module (ECM) or transmission control module (TCM). The VSS is responsible for monitoring the speed of the vehicle and relaying this information to the ECM or TCM. A low input signal suggests that the vehicle speed is below the expected range.
P0502 Vehicle Speed Sensor “A” Low Input
Code symptoms P0502.
1. Check engine light is illuminated on the dashboard.
2. Inaccurate or erratic speedometer readings.
3. Issues with transmission shifting, such as harsh or delayed shifts.
4. Loss of anti-lock brake system (ABS) functionality.
5. Cruise control may not function properly.
6. Odometer may not display correct mileage.
This code is common in brands such as:: Chevrolet, Renault, Ford, Toyota, Nissan, Mercedes Benz, Honda.
Causes of the code P0502.
1. Faulty vehicle speed sensor (VSS).
2. Damaged or corroded wiring or connectors in the VSS circuit.
3. Broken or loose reluctor ring (toothed wheel) on the vehicle’s transmission or wheel hub.
4. ECM or TCM software issues.
5. Faulty instrument cluster (rare).
Code Solutions P0502.
1. Use a diagnostic scanner to verify the code and pinpoint the issue with the VSS.
2. Inspect the VSS wiring and connectors for damage, corrosion, or loose connections. Repair or replace as necessary.
3. Test the VSS using a multimeter to check for proper voltage and resistance.
4. Check the reluctor ring for damage or missing teeth. Replace if necessary.
5. Update the ECM or TCM software if applicable.
6. Clear the trouble codes and test drive the vehicle to verify that the issue has been resolved.
7. If the problem persists, further diagnosis may be needed, and consulting a qualified mechanic is recommended. They can perform advanced tests and inspections to identify the root cause of the issue.