What it means
The HV battery pack coolant pump A reports a supply voltage circuit high condition. Battery thermal management may be impaired.
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 receives operating power through its supply-voltage circuit. P0C4D sets when the module detects that this supply is higher than expected, which may result from a short to voltage, a supply fault, or a problem with the pump driver.
Common causes
Most likely first.
- Short to voltage in the pump supply or sense circuit
- Faulty supply circuit or pump driver
- Poor connector connection
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 related pump codes, then compare any live supply-voltage reading with pump A's commanded state.
- With the vehicle powered down as specified by the manufacturer, inspect pump A's supply and sense connectors for loose, corroded, or damaged terminals.
- Check the accessible supply and sense wiring for damage or contact with another voltage source.
- Test the circuit for a short to voltage and verify the supply at the manufacturer's specified points using its wiring diagram and procedure.
- If wiring and connections pass, test the supply circuit and pump driver against the manufacturer's specification to identify the source of the high reading.
Common fixes
- Secure a loose pump A supply connector.
- Repair wiring shorted to voltage.
- Repair or replace damaged connector terminals or supply wiring.
- Repair the supply circuit or replace the pump driver if testing confirms the fault.
Can I keep driving?
Avoid heavy loads and charging until the pump supply fault is diagnosed because battery cooling control may be affected. Stop if power is reduced or a battery-temperature 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.