What it means
The hybrid control module detects that battery pack coolant pump A is running above the calibrated maximum speed without load. Indicates dry running due to coolant loss or air ingestion.
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 A circulates coolant through the battery thermal-management loop. The hybrid control module monitors pump speed and load; this code sets when pump A spins faster than its calibrated limit without the expected coolant load, suggesting coolant loss or air entering the pump.
Common causes
Most likely first.
- Coolant loss in battery loop
- Air drawn into pump suction
- Pack cell imbalance approaching service threshold
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
- Review freeze-frame data and live data for pump A speed, command, battery temperatures, and related battery-cooling faults.
- Check the battery-loop coolant level and look for visible leaks or signs of air entry, using the manufacturer's high-voltage safety procedures.
- Inspect pump A's accessible hoses and connections for looseness, leaks, kinks, or a suction-side gap that could draw in air.
- Inspect pump A's connector and wiring, then compare commanded and reported pump speed with scan-tool data.
- If the loop is full and sealed but overspeed persists, check for air or restriction using the manufacturer's bleeding and testing procedures.
Common fixes
- Repair a leaking or loose battery-loop hose or connection.
- Refill and bleed the battery cooling loop using the manufacturer's procedure.
- Repair pump A wiring or connector faults that produce an incorrect speed signal.
- Replace pump A if it continues to run above its specified speed without load after loop faults are corrected.
- Investigate battery-pack imbalance only if separate diagnostic codes or measurements support it.
Can I keep driving?
Battery cooling may be impaired, with reduced power or charging and possible further restriction if the pack overheats. Avoid charging and high-load driving until the coolant-loss or air-ingestion cause is corrected; stop if a battery or cooling 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.