What it means
The control module monitors the commanded operation and detected performance of hybrid/EV battery pack coolant pump B. It sets this code when pump operation does not meet the expected performance.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Battery pack coolant pump B circulates coolant through the hybrid or EV battery cooling loop. The control module compares commanded pump operation with detected performance and sets this code when pump B does not move coolant as expected, even if its electrical circuit appears to work.
Common causes
Most likely first.
- Coolant pump output degraded
- Air in the coolant loop
- Restricted coolant flow
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Save freeze-frame data and review pump B command, speed or status, and battery coolant temperatures to identify when performance fell short.
- Inspect the battery coolant loop around pump B for leaks, kinked hoses, damaged connectors, or signs that coolant flow is obstructed.
- Check the coolant level and look for signs of air in the loop, using the manufacturer’s method for checking and bleeding the system.
- Command pump B on with a suitable scan tool and confirm that it runs and produces the expected circulation under the manufacturer’s procedure.
- If flow remains low, test pump B output and inspect the loop for restrictions before deciding whether the pump has degraded.
Common fixes
- Correct coolant level or bleed air from the battery coolant loop using the specified procedure.
- Remove an identified restriction or repair a kinked or damaged hose in the pump B flow path.
- Repair a leak that is allowing air into the loop.
- Replace pump B if it runs poorly or fails the specified flow or performance test.
Can I keep driving?
Avoid strenuous driving and high-power charging if the hybrid system warns of overheating or reduces power; poor battery cooling can lead to further power limits or charging problems. Have the cooling fault diagnosed promptly.
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.