The P0878 trouble code indicates that there is a high voltage condition detected in the transmission fluid pressure sensor or switch “D” circuit.
P0878 Transmission Fluid Pressure Sensor/Switch “D” Circuit High
Code symptoms P0878.
1. Illumination of the Check Engine Light (CEL).
2. Harsh or delayed shifting from the transmission.
3. Transmission may fail to shift gears properly.
4. Reduced fuel efficiency.
5. Transmission overheating may occur in severe cases.
Causes of the code P0878.
1. Faulty transmission fluid pressure sensor or switch “D.”
2. Short to voltage in the wiring harness.
3. Corrosion or poor connections in the circuit.
4. High transmission fluid pressure due to a blockage or internal mechanical issue.
5. Problems with the transmission control module (TCM).
Code Solutions P0878.
1. Repair or replace any damaged wiring or connectors in the circuit.
2. Ensure good electrical connections and clean any corrosion from connectors.
3. If there is a blockage causing high transmission fluid pressure, diagnose and repair the underlying issue.
4. Replace the transmission fluid pressure sensor or switch “D” if it’s found to be faulty.
5. If internal transmission problems are suspected, further diagnostics or repairs may be necessary.
6. Clear the trouble codes from the vehicle’s computer after repairs are complete.
7. Test drive the vehicle to confirm that the issue has been resolved.