The P0C48 code in your 2021 Toyota Highlander Hybrid indicates a malfunction in the auxiliary transmission fluid pump motor. This electric pump maintains transmission fluid pressure when the engine is off during hybrid operation.
Auxiliary Pump Function
In hybrid vehicles, the engine frequently shuts off (EV mode, stop-start). The auxiliary electric pump maintains hydraulic pressure in the transmission during these engine-off periods, enabling smooth engagement when needed.
Common Causes of P0C48
- Auxiliary pump motor failure
- Pump control circuit issues
- Low transmission fluid
- Fluid contamination
- Wiring damage to pump
- Transmission control module fault
Symptoms of Auxiliary Pump Issues
- Harsh engagement from stop
- Delayed acceleration from EV mode
- Check engine light on
- Transmission warning
- Clunk when engine restarts
- Reduced EV mode operation
Highlander Hybrid Experience
The Highlander Hybrid's seamless transitions between electric and gas power require the auxiliary pump. P0C48 can make these transitions noticeably rough.