April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P0604: Internal Control Module Random Access Memory (Ram) Error: Notes

DTC detecting condition:

Immediately at fault recognition

Trouble symptom:

TCM RAM is faulty.

CAUTION: After servicing or replacing faulty parts, perform the last step of the basic diagnostic procedure, Ref. to TRANSMISSION (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .

CHECK DTC.
1. Using the Subaru Select Monitor, perform the clear memory. Ref. to COMMON (DIAG)>CLEAR MEMORY .
2. Read the DTC using Subaru Select Monitor, Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
Is DTC P0604 displayed?

Yes: Replace the TCM. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>TRANSMISSION CONTROL MODULE (TCM) .

No: Current condition is normal. Check for interference from noise, etc.