Internal Control Module ROM Error
What does P0605 mean?
The P0605 code means the vehicle's onboard diagnostic system has detected: Internal Control Module ROM Error. This is a critical severity code.
Common Symptoms
- Check Engine Light illuminated
- Engine may not start
- Complete loss of engine management
- All adaptive values lost
Probable Causes (Ranked by Likelihood)
- Corrupted ROM in the ECM/PCM Very High
- Failed ECM programming corrupting ROM High
- ECM hardware failure Moderate
- Electrical damage from jump starting or arc welding on vehicle Low
Step-by-Step Diagnostic Procedure
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Attempt to reflash the ECM with factory software
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Check for voltage issues that may have damaged the ECM
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Verify ECM power supply and grounds
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If reflashing fails, the ECM ROM chip has permanently failed
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Replace the ECM/PCM and program with the correct calibration
Frequently Asked Questions
Can I drive with code P0605?
Do not drive. Internal control module errors can cause unpredictable engine behavior. Have the vehicle towed to a shop.
Does P0605 mean I need a new ECM?
Not always. Some internal module errors can be resolved by reprogramming or reflashing the ECM with factory software. However, hardware failures (RAM, ROM, processor) typically require ECM replacement.
How much does an ECM replacement cost?
ECM replacement typically costs $300-$1500 including the part and programming. The ECM must be programmed with the correct calibration and vehicle options for your specific VIN.