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.
High severity. Can I keep driving?Do not rely on the car for trips: it may not start, or it may stall or go into limp mode while driving. If it drives poorly or is in reduced-power mode, have it towed.
Symptoms
- 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
Most likely causes
- Interrupted or faulty reprogramming
- Faulty module software (update available)
- Defective flash memory in the module
- Low voltage, voltage dips or a poor ground or supply at the module
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
- It can trigger limp mode.
- It affects emissions.
What each character of P0601 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 6: Control modules and outputs
- 01: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0601?
Do not rely on the car for trips: it may not start, or it may stall or go into limp mode while driving. If it drives poorly or is in reduced-power mode, have it towed.
What causes code P0601?
The most common causes are: interrupted or faulty reprogramming; faulty module software (update available); defective flash memory in the module.
Related codes
- P0602Control Module Programming Error
- P0603Internal Control Module Keep Alive Memory (KAM) Error
- P0604Internal Control Module Random Access Memory (RAM) Error
- P0605Internal Control Module Read Only Memory (ROM) Error
- P062FInternal Control Module EEPROM Error
- P0606Control Module Processor
Sources
- law.cornell.edu: 13 CCR 1968.2
- gsi.ext.gm.com: 25OBDG03A
- gsi.ext.gm.com: 25OBDG03B
- static.nhtsa.gov: MC 10120237 9999
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.