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.
Basic Diagnostic Procedure: Procedure
- CHECK ENGINE START FAILURE
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- Ask the customer when and how the trouble occurred using the interview check list. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>Check List for Interview>CHECK .
- Start the engine.
Does the engine start?
Yes : Go to 2.
No : Inspection using "Diagnostics for Engine Starting Failure". Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTICS WITH PHENOMENON .
- CHECK ILLUMINATION OF MALFUNCTION INDICATOR LIGHT
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Check the illumination status of malfunction indicator light.
Does the malfunction indicator light illuminate?
Yes : Go to 3.
No : Check using "Warning Light Illumination Pattern". Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>WARNING LIGHT ILLUMINATION PATTERN .
- CHECK COMMUNICATION STATUS
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- Turn the ignition switch to OFF.
- Connect the Subaru Select Monitor or general scan tool to the data link connector.
- Turn the ignition switch to ON, and run the Subaru Select Monitor or general scan tool.NOTE:
- SUBARU SELECT MONITOR
For detailed operation procedures, refer to "Help" of application.
- General scan tool
For detailed operation procedures, refer to the general scan tool operation manual.
- SUBARU SELECT MONITOR
Does Subaru Select Monitor or general scan tool communicate with vehicle normally?
Yes : Go to 4.
No : Inspection using "Basic Diagnostic Procedure" of LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
- CHECK DTC
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Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (diag)>DIAGNOSTIC TROUBLE CODE (DTC) .
Is DTC for [Engine] displayed? (Current malfunction)
Yes : Save DTC and freeze frame data, then repair the trouble cause. Ref. to COMMON (diag)>DIAGNOSTIC TROUBLE CODE (DTC) . Ref. to COMMON (diag)>FREEZE FRAME DATA .
After repair, go to the next step.
No : Go to 5.
No : Repair the related parts.
NOTE: If DTC is not shown on display although the malfunction indicator light illuminates, perform the diagnosis of malfunction indicator light circuit or combination meter. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>WARNING LIGHT ILLUMINATION PATTERN . - FINAL CHECK
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- Connect all connectors.
- Using the Subaru Select Monitor or a general scan tool, perform the clear memory of [Engine]. Ref. to COMMON (diag)>CLEAR MEMORY .
- Execute the inspection mode. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>INSPECTION MODE .
- Read the readiness code of [Engine] using Subaru Select Monitor and check that the concerned DTC is completed. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>ALL READINESS DIAGNOSTIC CODE(S) .
- Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (diag)>DIAGNOSTIC TROUBLE CODE (DTC) .
Is DTC for [Engine] displayed? (Current malfunction)
Yes : Check the connection of connector. If there is no faulty connector, perform the diagnosis for the displayed DTCs. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC) .
No : Finish the diagnosis.
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.