P0604 Internal Control Module Random Access Memory (RAM) Error

P0604 points to an internal control module random access memory error. The module reports a fault validating internal RAM operation.

Code details

Generic OBD-II · P0

System: Computer
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not condemn the controller without proving power and ground integrity; unstable voltage can create module-memory codes.

Symptoms of P0604

Check-engine light, sometimes with several unrelated codes at once.
Warning lights, a no-start, or intermittent electrical faults.
Communication or module-reset problems on a scan tool.

Common causes of P0604

Low battery voltage, poor grounds, corroded connectors, or blown fuses.
Wiring or network (CAN bus) faults between modules.
A module software/programming issue, or rarely a failed controller.

Useful checks before replacing parts

Verify clean battery voltage, charging stability, grounds, fuses, module power feeds, and connector condition.
Check for water intrusion, aftermarket electronics, failed programming, or service bulletins tied to controller memory faults.
Confirm whether the code returns after voltage and connector checks before replacing or reprogramming the module.

Related OBD-II codes

These nearby computer entries can help compare wording and pin down the fault area.