P0C1BElectric/Auxiliary Transmission Fluid Pump Control Module Internal Temperature Too High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0C1B is a protection code: the electronics that drive the auxiliary transmission fluid pump measure a valid but excessive internal temperature. No manufacturer documents this exact code publicly. GM shows the same function on the 2016 Cadillac ELR pump controller under its own code P1E37, an in-range overtemperature above 98 °C that could damage the inverter, checked only when the sensor itself is plausible. A Honda patent for a CVT pump explains the reaction: once the board temperature passes a limit, the control unit opens the pump relay and keeps the pump off until the fluid has cooled. The pump then stops, so start-stop and pressure support are lost. P0C1C to P0C1F cover faults of the temperature sensor itself and must be excluded first.
- What you may notice
- Engine auto-stop temporarily unavailable
- Transmission or hybrid warning, MIL depending on manufacturer
- Harsh engagement when driving off after a stop
- Likely causes
- LikelyHigh transmission fluid temperature from heavy load, towing or a weak fluid cooler
- PossiblePump running against high resistance (binding, clogged filter) and heating its driver
- RarePoor heat transfer from the module (mounting, contamination) or internal module fault
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €1,800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.