P0C21 Possible Causes
- Faulty auxiliary transmission fluid pump
- Auxiliary transmission fluid pump harness is open or shorted
- Poor electrical connection in auxiliary transmission fluid pump circuit
What Does It Mean?
How to Fix Code P0C21
Check the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.
P0C21 Possible Symptoms
Check engine light on (or service engine soon warning light)
P0C21 Meaning
The engine control module (ECM) monitors the auxiliary transmission fluid pump. The ECM sets the OBDII code when the auxiliary transmission does not meet factory specifications.