What it means
The second coolant pump runs even when no command is active. Driver is stuck on or the wire is shorted to a permanent supply.
At a glance
- Usually lights the check-engine light
How it works
Coolant Pump B circulates coolant through a separate vehicle-specific loop, and its controller should switch the pump on only when needed. P261E sets when the pump appears to remain on without a command, which can result from a stuck controller driver, a control wire shorted to permanent battery power, or a pump that does not stop freely.
Common causes
Most likely first.
- ECU output driver stuck on
- Control wire shorted to a permanent B+ supply
- Carbon or debris buildup preventing free movement
Symptoms
- Check-engine light
- Pump may continue running after the engine is off
- Battery may discharge if the pump keeps running
How to diagnose it
- Check freeze-frame data and live pump-command status to confirm whether Pump B was meant to be off when the fault set.
- After shutdown, observe whether Pump B continues running and note how long it remains on, following the vehicle's normal cooling behavior.
- Inspect the Pump B control wire and connector for a short to a permanent power feed, damaged insulation, or corroded terminals.
- Use the wiring diagram and manufacturer's procedure to determine whether the controller is still supplying power when the pump is commanded off.
- If the circuit loses its command correctly but the pump continues to run, check for a mechanical sticking fault in the pump.
Common fixes
- Repair a control wire shorted to permanent battery power.
- Clean and secure corroded or loose Pump B connector terminals.
- Replace or repair a controller with a confirmed stuck-on output.
- Repair or replace Pump B if it mechanically sticks on.
Can I keep driving?
If Pump B keeps running after its normal shutdown period, avoid leaving the vehicle parked for long and monitor the battery; disconnecting components without the service procedure can disrupt cooling. A continuously powered pump can drain the battery, while a pump fault may also affect its cooling loop.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.