P0605 Internal Control Module Read Only Memory (ROM) Error

P0605 points to an internal control module read-only memory error. The module reports a fault with internal stored program memory or its validation.

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 treat internal-module codes casually; replacement may require programming, immobilizer setup, and diagnosis of why the failure occurred.

Symptoms of P0605

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 P0605

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 battery voltage, charging stability, grounds, fuses, power feeds, and connector condition at the control module.
Check for water intrusion, aftermarket tuning, failed programming, or service bulletins that apply to module memory faults.
Confirm whether reprogramming is available before replacing the module.

Related OBD-II codes

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