P0605 - Internal Control Module ROM Error
The P0605 code indicates that the Engine Control Module (ECM) has detected an internal read-only memory (ROM) error. This means the ECM's firmware or calibration data is corrupted or malfunctioning. The ECM relies on ROM to store critical programming for engine operation, and a failure here can cause erratic behavior or prevent the engine from starting. This is a serious issue as it directly affects the computer that controls the engine.
01. Most Common Causes
- Faulty ECM due to internal component failure
- Corrupted ECM software or firmware
- Voltage spikes or electrical surges damaging the ECM
- Moisture or corrosion inside the ECM
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine may not start or stalls
- Poor engine performance, misfires, or hesitation
- Transmission shifting issues (if integrated)
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for other related codes.
Step 2: Inspect the ECM for physical damage, corrosion, or water intrusion.
Step 3: Check battery voltage and charging system for proper operation (12.6V engine off, 13.5-14.5V running).
Step 4: Attempt to reprogram the ECM with the latest manufacturer software using a professional scan tool.
Step 5: If reprogramming fails, replace the ECM and perform necessary programming/immobilizer relearn.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The ECM controls critical engine functions, and a ROM error can cause sudden stalling or loss of power, leading to a crash.
How much does it cost to fix?▼
Repair costs typically range from $500 to $1500, including parts (new or remanufactured ECM) and labor for programming and installation.