P0601Internal Control Module Memory Checksum Error
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- The module continuously calculates a checksum over its program and calibration memory (flash) and compares it with the stored value; on newer units the flash error correction also reports bit errors it cannot repair. A mismatch means the stored software is corrupted. GM sets P0601 in the engine module after one failed pass (or five once the first pass is complete) and turns on the lamp in the first trip; in body modules after two trips. Ford reports the same check as P0605, while GM, VW and Mazda use P0601. Typical causes are an interrupted reflash and manufacturer software errors – VW (2.0 TFSI) and Mazda (MX-5 2013) fixed it by reprogramming. The code alone does not say which module set it – the scan tool shows whether it is the engine, transmission, brake or body module.
- What you may notice
- Check engine light on
- Often no change in driving
- Possibly no start or limp mode if the software is badly damaged
- Transmission limp mode if the transmission module is affected
- Likely causes
- LikelyInterrupted or faulty reprogramming
- PossibleFaulty module software (update available)
- PossibleDefective flash memory in the module
- RareLow voltage, voltage dips or a poor ground or supply at the module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.