P0605 — Control module ROM error

P0605: Control module ROM error — what it means, the affected system and what to check before replacing parts.

Meaning, symptoms, causes and checks

The self-test reports a fault associated with read-only program memory (ROM). The memory type distinguishes this code from KAM and RAM faults. The definition does not establish whether programming integrity or internal hardware is the root cause.

Affected system: Control module self-diagnostics

Symptoms

  • Difficult starting; stalling and reduced power.

Possible causes

  • Corrupted firmware, internal ROM failure or voltage surge.

What to check

  • Check supplies, grounds, fuses and charging before ROM/software evaluation.

Also written as: P0605-00, P060500, PO605 (some scan tools add the fault-type byte, e.g. -00).