OBD-II code · Powertrain (generic)
P0604 Internal Control Module Random Access Memory (RAM) Error
ECU self-test detected a RAM fault during runtime checks. This is an internal ECU defect; replacement or reflash with manufacturer support is generally required.
Is it safe to drive with P0604?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyECU internal RAM fault
- Less likelyModule software outdated, reflash may resolve
- Less likelySupply voltage outside specification
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Usually unaffected
- Parts involved
- Ecm
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.