P0604
- Powertrain
- Generic (SAE)
Get it looked at now
Driving may cause further damage or leave you stranded. Arrange service promptly rather than waiting.
Internal Control Module Random Access Memory (RAM) Error
This code is in our catalogue but has not yet been through editorial review, so the guidance below is limited to what our structured data supports. We publish deeper diagnostic content only after a code has been reviewed — here is why.
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.
A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.
- Safe to drive
- Driving may cause further damage or leave you stranded. Arrange service promptly rather than waiting.
- Urgency
- Get it looked at now
- Will it pass emissions
- Not affected
- Check engine light
- Solid
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Many vehicles show no symptom at all beyond the warning light. The absence of a symptom does not mean the fault is not real.
| # | Cause | How often | Component |
|---|---|---|---|
| 1 | ECU internal RAM fault | Very common | — |
| 2 | Module software outdated, reflash may resolve | Occasional | — |
| 3 | Supply voltage outside specification | Occasional | — |
Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.
- ECM
- Definition
- Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
- Diagnostic guidance
- Written and reviewed in-house. See our editorial policy.
- Review status
- Awaiting review
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