P0C1B code meaning
Electric/Auxiliary Transmission Fluid Pump Control Module Internal Temperature Too High
Powertrain system Generic code P0Cxx codes Check engine light
What P0C1B means
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.
P0C1B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0C1B
- Engine auto-stop temporarily unavailable
- Transmission or hybrid warning, MIL depending on manufacturer
- Harsh engagement when driving off after a stop
Common causes of P0C1B
- Most 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
- Less likelyPoor heat transfer from the module (mounting, contamination) or internal module fault
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Aux trans pump control module
What each part of P0C1B means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| C | Area: hybrid propulsion. |
| 1B | The exact fault in that area. |
What to do next
- Note P0C1B and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0C1B
What does P0C1B mean?
P0C1B means "Electric/Auxiliary Transmission Fluid Pump Control Module Internal Temperature Too High". P0C1B is a protection code: the electronics that drive the auxiliary transmission fluid pump measure a valid but excessive internal temperature. It is a generic code, so it means the same on every make.
Is it safe to drive with P0C1B?
Drive gently and only to a workshop. With P0C1B the car can go into limp mode (reduced power) to protect itself.
Will P0C1B fail an emissions test?
Yes, it can. P0C1B is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0C1B to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will P0C1B clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.