What it means
Motor electronics coolant pump B reports a stuck/stalled condition. Power electronics cooling is impaired.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Motor electronics coolant pump B circulates coolant through a power-electronics cooling circuit. The control module sets this code when pump B is detected as stuck or stalled instead of turning as commanded, so coolant flow through its circuit may be lost.
Common causes
Most likely first.
- Pump impeller jammed
- Motor seized
Symptoms
- Check-engine or hybrid-system warning
- Power limited warning
- Reduced performance under load
How to diagnose it
- Review freeze-frame data and live pump B command and speed to confirm that the stall occurs while pump B is being asked to run.
- With the vehicle safely powered down, inspect pump B's impeller area and coolant hoses for debris, kinks, damage, or signs of a blockage.
- Check the coolant level and look for contamination or debris that could jam pump B.
- Inspect pump B's connector and wiring for looseness, corrosion, or heat damage that could prevent the motor from turning.
- Measure pump B supply voltage under command and compare it with the manufacturer's specification to distinguish a stalled motor from a power problem.
- If supply and coolant path are sound, test whether pump B's motor turns and its speed feedback responds according to the manufacturer's procedure.
Common fixes
- Remove an accessible obstruction from pump B's coolant path and correct any kinked hose.
- Correct low coolant or contamination in pump B's loop and bleed it using the specified procedure.
- Repair a damaged connector or wiring fault preventing pump B from receiving power.
- Replace pump B if its impeller is jammed internally or its motor remains seized with correct supply.
Can I keep driving?
Do not put the vehicle under heavy load because a stalled pump B can reduce power-electronics cooling and lead to power limitation or overheating. Stop safely if a hybrid-system or power-limited 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.