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DTC codes / P0Cxx · Hybrid propulsion / P0C2D

P0C2DElectric/Auxiliary Transmission Fluid Pump Control Module Feedback Signal Low

P0C2D means the electric or auxiliary transmission fluid pump control module is reporting a feedback signal voltage that is lower than the manufacturer's expected range. The transmission control module (TCM) or pump control module monitors this feedback circuit to confirm the pump is receiving proper power and ground, and it sets this code when the signal stays below the calibrated threshold for a set time.

SystemPowertrain
Code typeGeneric (all makes)
SeverityHigh
Fix difficultyProfessional
AreaHybrid propulsion

Symptoms you may notice

  • Illumination of the check engine light or transmission warning light, often with no other symptoms besides the warning light
  • The transmission may enter limp mode or fail-safe mode with harsh or delayed shifting
  • Loss of hybrid or electric vehicle propulsion if the auxiliary pump is needed to maintain fluid pressure when the engine is off
  • The vehicle may refuse to start or may shut down the electric drive system
  • A noticeable whine or lack of pump operation when the vehicle is in electric-only mode or during auto-stop events
  • Reduced fuel economy or poor drivability because the transmission cannot maintain line pressure

Common causes, most likely first

  1. A faulty electric/auxiliary transmission fluid pump control module, often due to internal circuit failure
  2. Damaged, corroded, or disconnected wiring or connector at the pump control module or pump motor
  3. A short to ground or open circuit in the feedback signal wire between the pump control module and the TCM
  4. Low or contaminated transmission fluid causing the pump to draw excessive current and distort the feedback signal
  5. A failing auxiliary transmission fluid pump motor that draws too much current or has an internal short
  6. Poor ground connection for the pump control module or pump motor
  7. A software or calibration issue in the TCM or pump control module requiring a reflash or update

How to diagnose and fix it

  1. Verify battery voltage and condition, then check all fuses and relays that supply power to the auxiliary transmission pump control module
  2. Inspect the pump control module connector and pump motor connector for corrosion, loose pins, or water intrusion, and repair as needed
  3. Measure the feedback signal voltage at the pump control module connector with a multimeter and compare to the manufacturer's specification
  4. Check the feedback signal wire for continuity to ground and for shorts to ground or power, repairing any damaged wiring
  5. Test the auxiliary transmission fluid pump motor for excessive current draw or internal resistance, replacing it if out of specification
  6. If all wiring and the pump motor test good, substitute a known-good pump control module and recheck for the code
  7. After repairs, clear the code and perform a road test or relearn procedure as required by the manufacturer to confirm the fix

Feedback circuit checks before module replacement

  • A low feedback signal is often caused by a poor ground at the pump control module rather than a failed module, so always load-test the ground circuit first
  • Corrosion inside the pump control module connector can mimic a failed module and is frequently missed when only the module is replaced
  • The auxiliary pump may only run during auto-stop or electric-only operation, so the code may not set during a conventional test drive and requires a specific enable procedure
  • A weak or aging 12-volt battery can cause the pump control module to report a low feedback signal because the module's internal reference voltage drops under load
  • This code does not always mean the pump control module is defective; a shorted pump motor or chafed harness can pull the feedback signal low and set the same code

Can I keep driving with P0C2D?

Do not continue driving with this code because the auxiliary transmission pump may not operate, which can cause loss of propulsion or transmission damage in hybrid and electric vehicles. Have the vehicle towed to a qualified repair facility if it enters limp mode or refuses to move.

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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