P0605: Internal Control Module Read Only Memory (ROM) Error
What to do
Likely to run poorly or in a reduced-power mode. Needs a dealer or a module specialist — there is no serviceable part here. Ask for the supply and earths to be verified first, since that is the one thing that can make a healthy module report this and it costs minutes.
What this code means
The module's permanent program storage has failed its self-test — the memory holding the software itself rather than any learned values.
This is among the least ambiguous codes in the block: there is no sensor to test, no wiring to inspect, and nothing a driver has done to cause it. The module either needs reprogramming, if the contents are recoverable, or replacing and coding if they are not.
As with the other internal codes, confirm the supply and earths first. It is a cheap check and it occasionally saves a module.
Likely causes
Start here
- Failed control module · specialist
- Corrupted module software · specialist
Less common
- Low system voltage disrupting communication · moderate
- Water ingress into module · specialist
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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