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DTC codes / P09xx · Transmission / P094C

P094CHydraulic Pump Performance/Stuck Off

P094C indicates that the transmission control module (TCM) has detected a performance problem with the hydraulic pump, specifically that the pump is stuck in the off position or is not building pressure as commanded. The TCM monitors pump operation through pressure switches or speed sensors and sets this code when the pump fails to respond to activation commands within expected parameters.

SystemPowertrain
Code typeGeneric (all makes)
SeverityHigh
Fix difficultyProfessional
AreaTransmission

Symptoms you may notice

  • Illumination of the check engine light or transmission warning light, often with no other symptoms
  • Harsh or delayed gear shifts, especially when cold
  • Transmission slipping or failing to engage a gear
  • Limp mode activation with reduced power and limited gear selection
  • Whining or unusual noise from the transmission area
  • In some cases, the vehicle may not move at all if the pump is completely stuck off

Common causes, most likely first

  1. Low or contaminated transmission fluid causing pump cavitation or sticking
  2. Faulty hydraulic pump solenoid or control valve stuck closed
  3. Wiring damage or corrosion at the pump connector or TCM
  4. Internal pump mechanical failure, such as a stuck relief valve or worn gears
  5. Failed transmission pressure sensor providing incorrect feedback
  6. TCM software calibration issue or internal fault

How to diagnose and fix it

  1. Check transmission fluid level and condition; top off or replace fluid if contaminated
  2. Inspect wiring and connectors at the hydraulic pump and TCM for damage or corrosion
  3. Use a scan tool to command the pump on and monitor pressure sensor readings to verify operation
  4. Test the pump solenoid resistance and compare to manufacturer specifications
  5. Perform a pressure test at the pump test port to confirm actual hydraulic pressure
  6. If electrical and fluid checks pass, remove and inspect the pump for mechanical sticking or wear
  7. Reprogram or replace the TCM if all other components test good and the code persists

Don't overlook the pump solenoid circuit

  • A stuck-off pump is often caused by a failed solenoid rather than the pump itself, so testing the solenoid circuit first can save unnecessary pump replacement.
  • Contaminated fluid from a failing torque converter or cooler can lodge debris in the pump relief valve, mimicking a pump failure.
  • Some vehicles use an auxiliary electric pump for start-stop functionality; a fault in that circuit can set P094C even when the main pump is fine.
  • The TCM may set this code intermittently if the pump only sticks when cold, so a thorough road test with live data is essential.
  • Always check for related codes like P094D or P0868 before condemning the pump, as they can indicate a pressure control issue rather than a pump fault.

Can I keep driving with P094C?

Driving with P094C is not recommended because the transmission may enter limp mode or lose pressure, leading to internal damage. If you must move the vehicle, drive slowly and directly to a repair shop, avoiding heavy loads or high speeds.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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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