What it means
The control module detects that DC/DC converter performance is outside its expected range.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The DC/DC converter transfers power from the high-voltage hybrid battery to the 12-volt electrical system. The control module monitors converter performance and sets P0A94 when its output or operation is outside the expected range; wiring faults and inadequate cooling can produce the same performance problem as a failed converter.
Common causes
Most likely first.
- DC/DC converter fault
- Wiring or connection fault
- Cooling problem
Symptoms
- Check-engine or hybrid-system warning light
- Reduced hybrid performance
- 12-volt charging warning light
How to diagnose it
- Record freeze-frame data and check live 12-volt voltage and hybrid-system readings to determine whether converter performance changes with load or temperature.
- Inspect converter wiring, grounds, and connectors for looseness, corrosion, or heat damage, and check accessible cooling passages for obstruction.
- Test the 12-volt battery and compare voltage at the converter and battery to identify a weak battery or wiring loss.
- Check converter cooling and related pump operation if temperature-related performance changes are present.
- If external causes are ruled out, test DC/DC converter output and controls to the manufacturer's specification.
Common fixes
- Clean and secure converter wiring, grounds, and connectors.
- Repair a confirmed cooling problem affecting DC/DC converter operation.
- Replace a 12-volt battery that fails testing and is overloading the converter.
- Repair or replace the DC/DC converter if its output remains outside specification.
Can I keep driving?
Limit driving if the 12-volt charging warning is on or accessories are failing, because the battery may discharge and hybrid operation can become unreliable. Stop if the vehicle loses power or displays a shutdown warning.
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.