P0605 Internal Control Module Read Only Memory (ROM) Error
P0605 is a generic OBD2 powertrain code. It means “Internal Control Module Read Only Memory (ROM) Error” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker.
Ask the AI about P0605 on your car- System
- Powertrain (P)
- Code type
- Generic (SAE)
- Range
- P06xx
- Urgency
- High
What P0605 means
The engine computer runs self-tests on its own memory and processor, and one failed: a processor fault (P0606), a memory checksum error (P0601) or a read-only memory error (P0605).
Symptoms
- Sometimes nothing but the lamp
- Stalling, a no-start or limp mode
- Several unrelated codes, or erratic behavior
Most likely causes
- Low or unstable supply voltage and poor grounds
- Software that needs updating — many makers publish fixes for these codes
- Water damage or corrosion at the module or its connectors
- A failed control module
What to check first
- Check the battery voltage, the terminals and the engine grounds
- Ask a dealer whether there is a software update for your car
- Replace or repair the module only after power, grounds and software are ruled out — a new one usually has to be programmed to the car
Can I keep driving with P0605?
Limit driving — get it checked promptly
With caution. If the car runs normally, get it checked soon; if it stalls or goes into limp mode, don’t rely on it.
How P0605 breaks down
Powertrain. Engine, transmission, fuel and emissions — the codes behind the check engine lamp.
Generic code: defined by SAE, the same on every make.
Computer & output circuits.
The specific fault within this range.
Where to look: Computer & output circuits
The control modules themselves and the circuits they drive: internal memory and processor self-tests, sensor reference voltages, glow plugs, coolant pumps, relays and other outputs.
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Frequently asked
What does P0605 mean?
P0605 is a generic OBD2 powertrain code. It means “Internal Control Module Read Only Memory (ROM) Error” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker. The engine computer runs self-tests on its own memory and processor, and one failed: a processor fault (P0606), a memory checksum error (P0601) or a read-only memory error (P0605).
Can I drive with P0605?
With caution. If the car runs normally, get it checked soon; if it stalls or goes into limp mode, don’t rely on it.
What causes P0605?
Low or unstable supply voltage and poor grounds; Software that needs updating — many makers publish fixes for these codes; Water damage or corrosion at the module or its connectors; A failed control module.
How do I clear P0605?
Fix the cause first, then clear it with any OBD2 scanner or app. Once the fault is gone the car also clears it on its own: the check engine lamp goes off after the self-test passes on three drive cycles in a row, and the stored code ages out after about 40 warm-ups. Clearing without a repair only hides it for a while — and resets the readiness monitors an emissions inspection looks at.
Is P0605 the same on every car?
Yes. P0605 is a generic SAE J2012 code, so its definition is identical on every make and model. What differs is the cause behind it and the repair procedure, which depend on the engine — that’s why the assistant on this page asks for your car.
Guides
Definitions: the generic SAE J2012 codes from Brimly’s offline dictionary (data version 2026.09). Causes and advice are general guidance for all makes — the service information for your car has the last word.