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DTC codes / P26xx · Computer and output circuits / P261E

P261ECoolant Pump B Control Circuit Stuck On

P261E indicates that the powertrain control module (PCM) has detected a fault in the control circuit for coolant pump B, specifically that the circuit is stuck in the 'on' state. The PCM commands the pump on or off via a driver, and it monitors the circuit for expected voltage changes; when the circuit remains energized even after the command is removed, this code sets.

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

Symptoms you may notice

  • Illumination of the check engine light (malfunction indicator lamp, MIL) with no other noticeable symptoms
  • The coolant pump may run continuously even with the engine off, potentially draining the battery
  • Overheating may occur if the stuck-on condition prevents proper coolant circulation or if the pump fails shortly after
  • A whirring or humming noise from the coolant pump area that persists after the engine is shut off
  • Possible low coolant temperature readings if the pump runs excessively and cools the engine below normal operating range
  • In some cases, the engine may enter limp mode or set related codes due to the PCM's fault strategy

Common causes, most likely first

  1. Faulty coolant pump B control circuit wiring, such as a short to power or a chafed wire grounding the control line
  2. Failed coolant pump B relay that has welded its contacts closed, keeping the circuit energized
  3. Defective coolant pump B itself, where internal electronics or motor windings cause a continuous draw
  4. PCM driver failure, where the internal transistor for the control circuit is stuck in the on state
  5. Corrosion or water intrusion in the coolant pump connector, creating an unintended conductive path
  6. Aftermarket accessories or improper wiring repairs that backfeed voltage into the 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, then clear the code and test-drive to see if it returns
  2. Inspect the coolant pump B connector and wiring harness for signs of corrosion, chafing, or loose pins, repairing as needed
  3. Disconnect the coolant pump B electrical connector and measure voltage on the control circuit with the key on and engine off; it should be near zero volts when the pump is commanded off
  4. Test the coolant pump B relay by swapping it with an identical relay from a non-critical circuit and rechecking for the code
  5. Measure resistance across the coolant pump B motor terminals and compare to specifications; an open or shorted winding indicates a failed pump
  6. Backprobe the PCM connector at the coolant pump B control circuit and check for voltage when the pump is commanded off; voltage present suggests a short to power in the harness or a faulty PCM
  7. If all external circuits and components test good, replace the PCM and reprogram it according to the manufacturer's procedure

What a stuck-on coolant pump really means

  • A stuck-on coolant pump can drain the battery overnight because the pump continues to run after the engine is shut off, so a parasitic draw test is often the first clue.
  • The PCM may set P261E even when the pump operates normally during a key-on engine-off test, because the fault is intermittent and only occurs under specific temperature or voltage conditions.
  • Technicians sometimes replace the coolant pump only to find the real cause is a shorted wire in the harness near the exhaust manifold, where heat damage is common.
  • This code can be triggered by a failing coolant pump relay that sticks closed, which is often overlooked because the relay is not part of the pump assembly.
  • On vehicles with two coolant pumps, P261E refers specifically to pump B, so misdiagnosing it as pump A can lead to replacing the wrong component.

Can I keep driving with P261E?

You can usually drive short distances to a repair shop, but monitor the coolant temperature gauge closely and avoid heavy loads or long trips. If the engine begins to overheat, stop safely and shut it off to prevent damage.

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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