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DTC codes / P0Cxx · Hybrid propulsion / P0C1E

P0C1EElectric/Auxiliary Transmission Fluid Pump Control Module Internal Temperature Sensor Circuit Low

P0C1E indicates that the electric or auxiliary transmission fluid pump control module has detected an abnormally low voltage signal from its internal temperature sensor circuit. The control module uses this sensor to monitor its own operating temperature and will set this code when the signal falls below the expected range, typically indicating a short to ground or an open circuit within the sensor or its wiring.

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

Symptoms you may notice

  • Illumination of the check engine light or transmission warning light, often with no other noticeable symptoms
  • The auxiliary transmission fluid pump may fail to activate, leading to reduced cooling or lubrication during engine stop-start events
  • In some cases, the transmission may enter a fail-safe mode with harsh shifting or limited gear selection
  • Overheating of the transmission fluid pump control module if the fault causes continuous pump operation or prevents proper cooling
  • Intermittent operation of the auxiliary pump, which may cause delayed engagement or slipping under certain conditions

Common causes, most likely first

  1. A short to ground in the internal temperature sensor circuit wiring or connector
  2. An open circuit or high resistance in the sensor signal circuit, often due to a broken wire or corroded terminal
  3. Failure of the internal temperature sensor itself within the control module
  4. A faulty auxiliary transmission fluid pump control module, where the sensor circuit is integrated and cannot be serviced separately
  5. Poor electrical connections at the control module harness, such as loose pins or water intrusion
  6. Damage to the wiring harness from heat, vibration, or road debris

How to diagnose and fix it

  1. Verify the code with a scan tool and check for any related codes in the transmission control module (TCM) or auxiliary pump control module
  2. Inspect the wiring harness and connectors at the auxiliary transmission fluid pump control module for signs of damage, corrosion, or loose pins
  3. Measure the resistance of the internal temperature sensor circuit at the control module connector and compare to the manufacturer's specification
  4. Check for a short to ground or an open circuit in the sensor wiring by performing continuity and voltage drop tests
  5. If the sensor is integrated into the control module and tests confirm an internal fault, replace the auxiliary transmission fluid pump control module
  6. Clear the code and perform a road test to verify the repair, monitoring live data for the sensor signal if available

Don't Replace the Module Before Checking This

  • A low signal from the internal temperature sensor often results from a simple chafed wire grounding against the transmission case, so a thorough visual inspection of the harness routing can save an expensive module replacement.
  • The internal temperature sensor is frequently integrated into the auxiliary pump control module, meaning a sensor failure requires replacing the entire module, but aftermarket rebuilds or separate sensor kits may exist for some applications.
  • This code can be set intermittently by water intrusion into the control module connector, especially on vehicles that frequently drive through deep puddles or in wet climates.
  • A weak or failing battery or charging system can cause low reference voltage to the control module, mimicking a sensor circuit fault, so always verify battery and ground integrity first.
  • Do not confuse this code with P0C1D (high signal) or other auxiliary pump codes; the diagnostic path is different, and misreading the code can lead to unnecessary parts swapping.

Can I keep driving with P0C1E?

You can generally continue driving with this code, but avoid heavy loads or prolonged idling that could stress the transmission, and schedule diagnosis soon to prevent potential overheating or pump failure. If the transmission enters limp mode or you notice slipping or harsh shifting, stop driving and seek professional service.

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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