P0C20
Electric/Auxiliary Transmission Fluid Pump Phase U-V-W Circuit/Open
The auxiliary transmission fluid pump phase U-V-W output reports a circuit/open condition.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Common causes
Ordered by how often each turns out to be the cause.
- Open phase wireCommon
- Open motor windingPossible
- Pin pushed back out of connector bodyLess likely
Parts involved
- Aux Trans Pump Phase Uvw
- Aux Trans Pump Inverter
P0C20 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.