What it means
The second electric coolant pump is commanded on but does not run. Cooling demand of the connected loop is not satisfied.
At a glance
- Usually lights the check-engine light
How it works
Coolant Pump B circulates coolant through a separate vehicle-specific loop, and the controller can command it on when that loop needs cooling. P261B sets when Pump B is commanded to run but the controller detects that it is not operating as expected, consistent with a seized or obstructed pump.
Common causes
Most likely first.
- Pump motor seized by sediment
- Cracked rotor magnet decouples drive
- Carbon or debris buildup preventing free movement
Symptoms
- Check-engine light
- Possible overheating or reduced cooling in the loop served by the pump
How to diagnose it
- Review freeze-frame data and live coolant temperatures to see whether Pump B was requested and whether the loop temperature was rising.
- Identify Pump B's cooling loop from service information, then inspect its connectors and wiring for damage that could prevent operation.
- When safe, check whether the pump runs during a scan-tool command or the vehicle's specified activation test.
- Check the pump and loop for signs of restricted flow, sediment, or debris using the manufacturer's procedure.
- If the electrical supply and command are present but the pump does not turn or circulate coolant, confirm mechanical failure before replacement.
Common fixes
- Repair a loose or damaged Pump B connector or wiring fault found during inspection.
- Remove an obstruction or address sediment in the pump or its coolant loop as specified for the vehicle.
- Replace Pump B if its rotor or motor is seized or cannot circulate coolant.
Can I keep driving?
Do not continue driving if the Pump B loop's temperature rises or a related overheating warning appears; stop safely and let the system cool. Continued operation without circulation can overheat and damage the components in that 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.