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.
2021 Subaru Ascent BaseFACTORY OEM SERVICE PROCEDURE
Inspection Mode E
| DTC | Item | Condition |
|---|---|---|
| P0801 | REVERSE INHIBIT CONTROL CIRCUIT/OPEN | - |
| P0841 | TRANSMISSION FLUID PRESSURE SENSOR/SWITCH "A" CIRCUIT RANGE/PERFORMANCE | Perform inspection mode E three times |
| P0846 | TRANSMISSION FLUID PRESSURE SENSOR/SWITCH "B" CIRCUIT RANGE/PERFORMANCE | Perform inspection mode E three times |
| U0073 | CONTROL MODULE COMMUNICATION BUS OFF | - |
| U0100 | LOST COMMUNICATION WITH ECM/PCM "A" | - |
| U0122 | LOST COMMUNICATION WITH VEHICLE DYNAMICS CONTROL MODULE | - |
| U0128 | LOST COMMUNICATION WITH PARK BRAKE CONTROL MODULE | - |
| U0131 | LOST COMMUNICATION WITH POWER STEERING CONTROL MODULE | - |
| U0140 | LOST COMMUNICATION WITH BODY CONTROL MODULE | - |
| U0155 | LOST COMMUNICATION WITH INSTRUMENT PANEL CLUSTER (IPC) CONTROL MODULE | - |
| U0164 | LOST COMMUNICATION WITH HVAC CONTROL MODULE | - |
| U0401 | INVALID DATA RECEIVED FROM ECM/PCM "A" | - |
| U0416 | INVALID DATA RECEIVED FROM VEHICLE DYNAMICS CONTROL MODULE | - |
| U0417 | INVALID DATA RECEIVED FROM PARK BRAKE CONTROL MODULE | - |
| U0420 | INVALID DATA RECEIVED FROM POWER STEERING CONTROL MODULE | - |
| U0422 | INVALID DATA RECEIVED FROM BODY CONTROL MODULE | - |
| U0423 | INVALID DATA RECEIVED FROM INSTRUMENT PANEL CLUSTER CONTROL MODULE | - |
| U0424 | INVALID DATA RECEIVED FROM HVAC CONTROL MODULE | - |
| U1235 | LOST COMMUNICATION WITH EyeSight | - |
| U1433 | INVALID DATA RECEIVED FROM EyeSight | - |
Diagnostic procedure:
- Check the readiness code using Subaru Select Monitor and confirm that the diagnosis is not completed.
- Start the engine.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.