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DTC codes / P26xx · Computer and output circuits / P261F

P261FCoolant Pump A Control Circuit Stuck On

P261F indicates that the engine control module has detected a fault in the control circuit for coolant pump A, specifically that the circuit is stuck in the on state. The computer expects to be able to turn the pump on and off, but the circuit remains energized even when commanded off, which can lead to continuous pump operation and potential overheating of the pump or circuit.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaComputer and output circuits

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Coolant pump may run continuously even after the engine is shut off, draining the battery
  • Overheating if the pump is stuck off, but this code specifically indicates stuck on, so overheating is less likely unless the pump fails
  • Possible coolant leaks or pump noise due to continuous operation
  • Battery drain if the pump remains powered with the ignition off

Common causes, most likely first

  1. Faulty coolant pump relay or control module sticking closed
  2. Short to power in the control circuit wiring
  3. Failed coolant pump (internal short causing continuous operation)
  4. Engine control module internal fault
  5. Corroded or damaged connectors in the pump control circuit

How to diagnose and fix it

  1. Verify the code with a scan tool and check for any related codes in other modules
  2. Inspect the coolant pump control circuit wiring for shorts to power or damage
  3. Test the coolant pump relay for proper operation and replace if stuck closed
  4. Disconnect the pump and check if the circuit remains powered; if so, trace wiring for short to power
  5. Check the coolant pump for internal short and replace if necessary
  6. If all else checks out, diagnose the engine control module for internal faults

When the pump runs with the key off

  • A stuck-on coolant pump can drain the battery overnight, so check for parasitic draw if the code is present.
  • Some vehicles use the coolant pump for turbocharger cooling after shutdown, so continuous running may be normal for a short period; verify with service information.
  • A short to power in the control circuit can be caused by chafed wiring near hot exhaust components, which is often overlooked.
  • The code may set intermittently if the relay sticks only when hot, so testing when the fault is active is crucial.
  • Replacing the pump without checking the relay and wiring can lead to repeat failures if the root cause is a shorted circuit.

Can I keep driving with P261F?

Driving with this code is generally safe for short distances, but avoid leaving the vehicle parked for extended periods without checking for battery drain. Monitor coolant temperature and address the issue promptly to prevent pump failure or battery depletion.

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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