What it means
The hybrid/EV battery pack coolant pump B control circuit voltage is below the expected range.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Battery coolant pump B circulates coolant through the high-voltage battery thermal-management system. The control module monitors pump B's control-circuit voltage and sets P0E1B when it is below the expected range, which can indicate a short to ground, an internally shorted motor, or excessive resistance at a connector.
Common causes
Most likely first.
- Wire shorted to ground
- Internal motor short
- Connector pins corroded - high contact resistance
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
- Check freeze-frame and hybrid-system live data for battery temperature, pump B command, and any pump-speed or coolant-flow feedback associated with the low-circuit fault.
- With the vehicle powered down as specified by the manufacturer, inspect pump B's wiring and connector for chafing, moisture, corrosion, or damaged terminals.
- Use the manufacturer's wiring diagram and procedure to test the pump B control wire for a short to ground.
- Test pump B's motor and connector for an internal short or abnormal load according to the manufacturer's specification.
- If no short or motor fault is found, check connector contact resistance and verify module output using the manufacturer's diagnostic procedure.
Common fixes
- Repair pump B wiring that is shorted to ground.
- Clean or replace corroded pump B connector terminals.
- Repair damaged insulation or a poor pump B electrical connection.
- Replace pump B if its motor tests internally shorted.
Can I keep driving?
Pump B may not circulate coolant correctly, risking battery temperature limits that can reduce charging or vehicle power. Avoid heavy loads and stop safely if an overheating warning or severe power limitation 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.