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DTC codes / P0Cxx · Hybrid propulsion / P0CEC

P0CECHybrid/EV Electronics Coolant Pump A Control Circuit High

P0CEC indicates that the hybrid or electric vehicle electronics coolant pump control circuit is reporting a high voltage condition, meaning the pump driver or wiring has an open circuit, short to voltage, or the pump itself has failed. The computer detects this when the commanded pump output does not match the expected voltage or current feedback, typically seeing a voltage above the normal operating range.

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

Symptoms you may notice

  • Illumination of the check engine light or service vehicle soon message
  • Often no symptoms besides the warning light, especially if the pump still runs intermittently
  • Reduced hybrid system power or forced engine-only operation
  • Overheating warning for the hybrid electronics, leading to limited performance
  • Possible audible absence of the coolant pump running after shutdown
  • In rare cases, the vehicle may enter a fail-safe mode and refuse to start

Common causes, most likely first

  1. Failed hybrid/EV electronics coolant pump (open winding or internal fault)
  2. Open circuit in the pump power or ground wiring, including a broken wire or corroded connector
  3. Short to voltage on the pump control circuit, often from chafed wiring near hot or moving components
  4. Faulty pump control module or driver inside the hybrid control unit
  5. Blown fuse or fusible link supplying the coolant pump
  6. Poor electrical connection at the pump harness connector due to water intrusion or terminal fretting

How to diagnose and fix it

  1. Verify the stored code and check for any related codes in the hybrid control module before clearing anything
  2. Inspect the coolant pump fuse and relay, and test for power and ground at the pump connector with the key on
  3. Perform a visual inspection of the pump wiring harness for chafing, corrosion, or loose pins, especially near heat sources
  4. Use a scan tool to command the coolant pump on and off while monitoring the control circuit voltage and pump feedback
  5. Measure resistance across the pump motor terminals to check for an open winding, comparing to manufacturer specifications
  6. If wiring and power are good, substitute a known-good pump or perform a bidirectional test to confirm pump operation
  7. After repair, clear codes and verify the pump runs correctly during a road test with hybrid system active

Don't overlook the pump connector

  • A common cause of this code is a partially unseated or corroded connector at the pump, which can mimic a failed pump and lead to unnecessary replacement.
  • The code can set intermittently if the pump only fails when hot, so a cold resistance check may pass even though the pump is faulty.
  • Some vehicles use the same coolant loop for the inverter and battery, so a pump fault may also trigger unrelated temperature-related codes that distract from the real issue.
  • A short to voltage on the control circuit can be caused by wiring rubbing against a 12-volt source, often near the hybrid transaxle or under the hood.
  • Replacing the pump without checking the control module's driver circuit can result in a repeat failure if the module is internally damaged.

Can I keep driving with P0CEC?

It is not advisable to continue driving with this code because the hybrid electronics may overheat and cause expensive damage or a sudden loss of power. Limit driving to a short distance to a safe location or repair shop, and avoid heavy acceleration or long trips.

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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