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DTC codes / P0Cxx · Hybrid propulsion / P0C2A

P0C2AElectric/Auxiliary Transmission Fluid Pump A Motor Stalled

P0C2A indicates that the transmission control module (TCM) has detected a stalled condition in the electric motor that drives the auxiliary transmission fluid pump. The TCM monitors the pump motor's speed and current draw, and when the motor fails to rotate as commanded or draws excessive current without movement, it sets this code and typically disables the pump.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaHybrid propulsion

Symptoms you may notice

  • Illumination of the check engine light or transmission warning light
  • Often no symptoms besides the warning light, especially if the mechanical pump still provides adequate pressure
  • Harsh or delayed shifting when the engine is running and the auxiliary pump is needed
  • Loss of drive or reduced power if the vehicle relies on the auxiliary pump for start-stop or hybrid operation
  • Overheating of the transmission fluid under heavy load or low-speed conditions
  • Audible whining or grinding from the transmission area if the pump motor is seized

Common causes, most likely first

  1. Failed auxiliary transmission fluid pump motor (worn brushes, seized bearings, or open windings)
  2. Blown fuse or faulty relay supplying power to the pump motor
  3. Damaged or corroded wiring harness or connector at the pump motor
  4. Internal short or open circuit in the pump motor windings
  5. Faulty transmission control module (TCM) not commanding the pump correctly
  6. Low or contaminated transmission fluid causing increased pump load and motor stall
  7. Mechanical binding in the pump assembly or transmission fluid circuit

How to diagnose and fix it

  1. Check the fuse and relay for the auxiliary transmission fluid pump and replace if blown or faulty
  2. Inspect the wiring harness and connector at the pump motor for damage, corrosion, or loose pins; repair as needed
  3. Measure resistance across the pump motor terminals and compare to specification to check for open or shorted windings
  4. Command the pump on with a scan tool and verify motor operation and current draw; if no operation, proceed to component testing
  5. Check transmission fluid level and condition; service if contaminated or low
  6. If the motor fails electrical and operational tests, replace the auxiliary transmission fluid pump motor
  7. After repair, clear the code and perform a road test to verify the pump operates correctly and the code does not return

Before you replace the auxiliary pump motor

  • A weak or failing battery can cause the pump motor to stall due to low voltage, so always load-test the battery before condemning the motor.
  • The auxiliary pump often runs only during engine stop events in start-stop systems, so a stall may not be evident during a standard test drive.
  • Corrosion inside the pump motor connector is a frequent cause that mimics a failed motor, so inspect the pins carefully before replacement.
  • A seized pump motor can sometimes be freed by manually rotating it, but this is a temporary fix and the motor should be replaced if binding is found.
  • This code can be set by a faulty TCM driver circuit even when the motor is good, so verify the command signal with a scope if the motor tests fine.

Can I keep driving with P0C2A?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy loads, towing, or prolonged low-speed driving because the auxiliary pump may be inoperative and the transmission could overheat. If the vehicle enters limp mode or shifting becomes harsh, stop driving and seek professional service.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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