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 PRE-INSPECTION.
- Ask the customer when and how the trouble occurred using the interview check list. Ref. to TRANSMISSION (DIAGNOSTICS)>CHECK LIST FOR INTERVIEW .
- Before performing diagnostics, check the following items which might affect CVT problems.
- General inspection Ref. to TRANSMISSION (DIAGNOSTICS)>GENERAL DESCRIPTION>INSPECTION .
- Disconnection of harness connector
- Visual check for harness damage
- Oil leakage
- Stall test Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580)>STALL TEST .
- Secondary pressure test Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580)>SECONDARY PRESSURE (LINE PRESSURE) TEST .
- Transfer clutch pressure test Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580)>TRANSFER CLUTCH PRESSURE TEST .
- Time lag test Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580)>TIME LAG TEST .
- ROAD TEST Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580)>ROAD TEST .
- Inhibitor switch Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580)>INHIBITOR SWITCH .
Is the check result OK?
Yes: Go to 2.
No: Repair the items which may be affecting the CVT trouble.
- CHECK AT OIL TEMP LIGHT.
Turn the ignition switch to ON and wait for at least 2 seconds.
Does the AT OIL TEMP light illuminate?
Yes: Go to 3.
No: Check the AT OIL TEMP light.
- CHECK AT OIL TEMP LIGHT.
Start the engine and wait for 2 seconds or more.
Does the AT OIL TEMP light blink?
Yes: Go to 4.
No: Go to 5.
- CHECK DTC.
Read the DTC of [Transmission] using the Subaru Select Monitor. Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
NOTE: If the communication function of the Subaru Select Monitor cannot be executed properly, check the communication circuit. Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE FOR SUBARU SELECT MONITOR COMMUNICATION .Are any DTCs displayed?
Yes: Record the DTC, time stamp and freeze frame data. Go to 6.
No: Go to 5.
- PERFORM GENERAL DIAGNOSTICS.
- Inspect using "Diagnostic Procedure without Diagnostic Trouble Code (DTC)". Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITHOUT DIAGNOSTIC TROUBLE CODE (DTC) .
- Inspect using "Diagnostics with Phenomenon". Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTICS WITH PHENOMENON .
- Perform the road test. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580)>ROAD TEST .
- Read the DTC of [Transmission] using the Subaru Select Monitor. Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
Are any DTCs displayed?
Yes: Go to 6.
No: Finish the diagnosis.
- PERFORM DIAGNOSIS.
- Inspect by referring to "Diagnostic Procedure with Diagnostic Trouble Code (DTC)". Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC) .NOTE: For the DTC table, refer to "Diagnostic Trouble Code (DTC)". Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST .
- Repair or replace the cause of trouble.
- Using the Subaru Select Monitor, perform the clear memory of [Transmission]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
- Execute the inspection mode. Ref. to TRANSMISSION (DIAGNOSTICS)>INSPECTION MODE .
- Check the readiness code of [Transmission] using Subaru Select Monitor and confirm that the diagnosis is completed. Ref. to TRANSMISSION (DIAGNOSTICS)>ALL READINESS DIAGNOSTIC CODE(S) .
- Read the DTC of [Transmission] using the Subaru Select Monitor. Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
Are any DTCs displayed?
Yes: Inspect by referring to "Diagnostic Procedure with Diagnostic Trouble Code (DTC)". Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC) .
No: Finish the diagnosis.
- Inspect by referring to "Diagnostic Procedure with Diagnostic Trouble Code (DTC)". Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC) .
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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.
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