What it means
The vehicle bus reports loss of communication with the high-voltage battery coolant pump. Active battery cooling cannot be regulated; charging/discharging power may be limited to protect the cells.
At a glance
- Usually lights the warning light of the system that lost communication
- The engine or gearbox may go into limp mode
How it works
The hybrid or EV battery coolant pump circulates coolant to control the high-voltage battery's temperature. The vehicle controller monitors the pump's network messages; U02AE sets when those messages are lost, so active battery cooling cannot be reliably regulated.
Common causes
Most likely first.
- Bus wiring open or shorted
- Module without power or ground
- Module failed
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
How to diagnose it
- Scan the vehicle's modules for related network, battery-temperature, and pump faults, and review freeze-frame data for when communication stopped.
- Check live data for battery coolant pump communication, pump status, and battery temperature readings.
- With the vehicle powered down as directed by its manufacturer, visually inspect the pump connector and accessible low-voltage bus wiring for damage, corrosion, or loose connections.
- Have the pump's low-voltage power and ground circuits checked according to the manufacturer's procedure.
- Have the network wiring to the pump tested for an open, short, or poor connection using the manufacturer's procedure.
- If the wiring, power, and ground are sound, follow the manufacturer's diagnostics to confirm whether the coolant pump has failed.
Common fixes
- Reconnect or repair a loose or corroded pump connector.
- Repair damaged communication wiring to the battery coolant pump.
- Restore the pump's low-voltage power or ground supply.
- Replace the battery coolant pump if testing confirms it has failed.
Can I keep driving?
Do not continue normal driving or charging if a hybrid or EV battery-temperature or coolant warning is displayed; loss of active cooling can lead to reduced power or a protective shutdown. Follow the vehicle's warning instructions and arrange service 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.