What it means
Hybrid/EV electronics coolant pump B reports a control circuit/open condition. Power electronics cooling on this branch is impaired.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Electronics coolant pump B circulates coolant through its assigned hybrid or EV power-electronics cooling branch. The control module monitors the pump’s control circuit and sets this code when it detects an open circuit, so pump B may not run and that branch may lose cooling.
Common causes
Most likely first.
- Pump motor or driver fault
- Air or coolant level issue
- Pin pushed back out of connector body
Symptoms
- Check-engine or hybrid-system warning light
- Reduced power or limited hybrid operation
- Possible power-electronics overheating warning
How to diagnose it
- Read freeze-frame data and check pump B command, status, and temperature data, along with any cooling-system codes.
- When the vehicle is safely off, check the electronics-coolant level and look for leaks or signs of air in the pump B branch.
- Inspect pump B’s connector and harness for damage, corrosion, looseness, or a terminal pushed back into the connector body.
- Use the manufacturer’s procedure to check pump B power, ground, control wiring continuity, and connector contact under the specified conditions.
- If wiring and connections are sound, test pump B’s motor and driver operation against the manufacturer’s diagnostic procedure.
Common fixes
- Restore the specified coolant level and correct any leak or air entry using the manufacturer’s filling procedure.
- Reseat or repair a pushed-back, loose, or corroded pump B connector terminal.
- Repair an open or damaged pump B control-circuit wire.
- Replace pump B if its motor or driver fails the specified test.
Can I keep driving?
Limit driving and avoid heavy acceleration or sustained high loads because power electronics on pump B’s branch may overheat and the vehicle may reduce power. Stop safely if an overheating or hybrid-system warning appears.
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.