What it means
The hybrid/EV battery pack coolant pump B control circuit voltage is above 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 pack coolant pump B circulates coolant to control the hybrid or EV battery’s temperature. The control module monitors the pump B control circuit and sets this code when its voltage is higher than expected, which can happen if the wire is shorted to battery positive or the pump circuit is open or has a poor connection.
Common causes
Most likely first.
- Wire shorted to B+
- Open motor
- 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
- Save the freeze-frame data and check hybrid system codes and pump B command or status to see when the fault occurred.
- With the vehicle powered down as specified by the manufacturer, inspect pump B’s connector and harness for corrosion, damage, loose pins, or contact with a power wire.
- Check the pump B circuit for a short to battery positive and for continuity through the motor and wiring, following the manufacturer’s safety procedure.
- Compare circuit readings with the manufacturer’s specification, including connector voltage under the conditions that set the code.
- If wiring and pump checks pass, investigate the control module’s pump B output and verify coolant circulation using the manufacturer’s diagnostic procedure.
Common fixes
- Clean or repair corroded, loose, or damaged pump B connector terminals.
- Repair wiring shorted to battery positive or an open in the pump B circuit.
- Replace pump B if its motor circuit is open or the pump fails the specified test.
- Repair or replace the control module output only after confirming the pump and wiring are sound.
Can I keep driving?
Avoid driving if the vehicle limits power, warns of battery or hybrid system overheating, or will not charge normally; continued use can worsen battery thermal problems. If there are no severe warnings, keep trips short and arrange diagnosis 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.