The P0642 trouble code indicates that the sensor reference voltage “A” circuit is operating at a low voltage level. This circuit provides a reference voltage to various sensors in the vehicle, allowing them to function properly.
Sensor Reference Voltage “A” Circuit Low
Code symptoms P0642.
1. Check Engine Light (CEL) is illuminated on the dashboard.
2. Decreased engine performance or rough idling.
3. Poor fuel efficiency.
4. Vehicle may stall or have difficulty starting.
5. Other sensor-related trouble codes may be present.
This code is common in brands such as:: Chevrolet, Renault, Ford, Toyota, Nissan, Mercedes Benz, Honda.
Causes of the code P0642.
1. Faulty sensor reference voltage circuit wiring or connectors.
2. Corrosion or poor connections in the sensor reference voltage circuit.
3. A defective Engine Control Module (ECM) or Powertrain Control Module (PCM).
Code Solutions P0642.
1. Inspect the wiring harness and connectors associated with the sensor reference voltage “A” circuit for any signs of damage, corrosion, or loose connections. Repair or replace any damaged components as necessary.
2. Clear the trouble codes and perform a test drive to verify that the issue has been resolved. If the code persists, further diagnosis may be required, including testing the voltage output of the ECM or PCM.
3. It’s recommended to follow manufacturer-specific diagnostic procedures outlined in the vehicle’s service manual to accurately diagnose and repair issues related to the sensor reference voltage “A” circuit. If needed, seek assistance from a qualified technician or dealership.