Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0A94: Dc/Dc Converter Performance: Notes
DTC detecting condition:
Detected when two consecutive driving cycles with fault occur.
Trouble symptom:
- Auto Start Stop does not operate.
- When the Auto Start Stop restarts, the audio or navigation system is reset.
- Power for audio and navigation system will not turn on.
- Doors cannot be opened/closed with keyless access system.
- Illumination does not illuminate.
- Combination meter does not operate.
- A/C does not operate.
- VDC does not operate.
- EyeSight does not operate.
Wiring diagram:
Auto Start Stop Ref. to WIRING SYSTEM>AUTO START STOP .
- CHECK VEHICLE CONDITION
.
Turn the ignition switch to ON, and turn on the audio or navigation system.
Is it powered on?
Yes: Go to 3.
No: Go to 2.
- CHECK INPUT VOLTAGE OF DC/DC CONVERTER 1
.
Measure the voltage between DC/DC converter 1 and chassis ground.
Connector & terminal
(B12) No. 3 (+) - Chassis ground (-):
(B12) No. 5 (+) - Chassis ground (-):
Is the voltage 10 V or more?
Yes: Go to 3.
No: Check the following item and repair if necessary.
- Open or short to ground in harness of power supply circuit
- Blown out of fuse
- CHECK REPEATABILITY
.
- Using the Subaru Select Monitor, perform the clear memory of [Transmission]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY .
- Start the engine.
- Turn the ignition switch to OFF and wait for 10 seconds.
- Using the Subaru Select Monitor, read the DTC of [Transmission] after repeating the procedure from step 2 to 3 two times. Ref. to AUTO START STOP (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
Is the same DTC as current diagnosis output?
Yes: Check for the poor contact of DC/DC converter 1 connector. Replace the DC/DC converter 1 if no fault is found. Ref. to STARTING/CHARGING SYSTEMS (H4DO)>AUTO START STOP DC/DC CONVERTER . Ref. to STARTING/CHARGING SYSTEMS (H4DOTC)>AUTO START STOP DC/DC CONVERTER .
No: The circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.
NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.