P0606 — Internal Control Module Read Only Memory (ROM) Error
Drivable short-term, but fix now to avoid damage.
What P0606 means
This code means the engine's computer detected an internal processor or Read Only Memory (ROM) fault during its self-check. ROM holds the permanent operating instructions, so an error here usually means a hardware problem inside the PCM, though bad grounds or low voltage can also be involved. Fixes typically require checking power and ground connections, reprogramming the module, or replacing the computer.
Common symptoms
- Check engine light is on
- Engine stalls or won't start
- Reduced power or limp mode
- Erratic or rough engine performance
- Multiple warning lights may appear
Common causes
- Internal processor or ROM fault in the control module
- Corroded or loose ground connections
- Low or unstable battery voltage
- Failed or interrupted software update
- Moisture or heat damage inside the computer
Typical repair cost
$150 – $1200
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0606 code?
It's not recommended. This code involves the engine's processor and core memory, so the car may stall or refuse to start at any moment. Drive only as far as needed to reach a shop for diagnosis.
How much does it cost to fix a P0606 code?
If it's a wiring or grounding issue plus reprogramming, expect $150 to $350. If the computer itself needs replacing and programming, the cost typically lands between $800 and $1,200 depending on the vehicle.
Is a P0606 code serious?
Yes, it's serious. The processor and ROM are central to running the engine and other systems, so a fault here can leave you stranded. Get it addressed quickly.
Can a bad ground cause a P0606 code?
Yes. Poor or corroded ground connections can cause the computer to fail its internal self-check and set this code. A technician should verify power and grounds before condemning the PCM.