What it means
The output driver for hybrid/ev battery pack coolant pump b reports current or junction temperature above its protection threshold.
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 is driven by an electronic output in the hybrid or EV control system. This code sets when the output driver reports excessive current or its own temperature exceeds a protection threshold while operating pump B, which can point to a binding pump, a short, or a failing driver.
Common causes
Most likely first.
- Pump motor or actuator drawing excessive current
- Control circuit short
- Faulty output driver
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 check whether the fault occurred when pump B was commanded on, along with any related pump or driver codes.
- With the vehicle powered down as specified by the manufacturer, inspect pump B’s connector and harness for shorts, damaged insulation, corrosion, or signs of overheating.
- Check whether pump B turns freely and inspect the coolant loop for conditions that could make the pump work harder, following the manufacturer’s safe procedure.
- Measure pump B current during a commanded operation and compare it with the manufacturer’s specification to distinguish excessive motor load from a control fault.
- If current and wiring are within specification but the driver still reports overcurrent or overheating, test the module output using the manufacturer’s procedure.
Common fixes
- Repair damaged or shorted wiring in the pump B control circuit.
- Repair a poor or corroded pump B connection that can disrupt the driver circuit.
- Replace pump B if it binds or draws excessive current during the specified test.
- Repair or replace the output driver or control module only after ruling out pump and circuit faults.
Can I keep driving?
Avoid driving or charging if power is limited or the vehicle reports a battery cooling or hybrid system fault, since pump B may not cool the battery adequately. Stop if the vehicle warns of overheating or is preparing to shut down, and arrange prompt diagnosis.
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.