What P0601 means
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.
How the engine computer detects it
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.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
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
Common causes
- Interrupted or faulty reprogramming Most likely
- Faulty module software (update available) Possible
- Defective flash memory in the module Possible
- Low voltage, voltage dips or a poor ground or supply at the module Less likely
How to diagnose P0601
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: engine control module, control module power supply, control module ground.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Vehicles that report P0601 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Chevrolet Impala | 2009 | 3 | 111k |
Counts of owner complaints to the NHTSA that mention P0601 (18 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 6
- Computer and output circuits
- 01
- Specific fault
Questions drivers ask
Can I drive with code P0601?
Drive gently and only as far as you need to. The engine computer may limit power to protect the engine, so avoid highways and heavy traffic until it's fixed. If the check engine light starts flashing, pull over.
Will my car pass an emissions inspection with P0601?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.