P0601: checksum and flash-memory integrity failures

P0601 is an internal memory-integrity code in the cited ECM and TCM examples. It can result from a calculated software/calibration checksum disagreeing with its stored value, or from the flash memory's error-correcting hardware detecting the specified error condition.

First-pass behavior differs from later checks

The checksum path uses one failure during the first pass, but five failures after that first pass is complete. A fault detected quickly during initialization and one detected later in operation can therefore arise through the same checksum monitor without sharing the same accumulation history.

The flash hardware path has its own failure count, listed as 254. It is not the same decision as the checksum comparison. The table states that failure counts clear when the controller shuts down, so restarting changes the counter context even if the underlying cause remains.

Establish the reporting module

The same code appears in both engine and transmission controller sections. The module address is essential evidence; the code alone does not identify the ECM as the defective component. Preserve the original module, status and associated internal faults before interpreting a subsequent clean read.

This summary provides no authorized reprogramming method or automatic replacement rule. It explains an internal self-check failure, not a particular external sensor problem. Verification should follow the applicable controller procedure and confirm successful memory checks through the relevant initialization and running stages, rather than treating disappearance immediately after clearing as proof of correction.

Source and applicability

Documented monitors in gm-2025-03a, model year 2025. These are module/calibration examples; vehicle, engine and transmission applicability must be confirmed independently. GM 2025-03a, page 357. GM 2025-03a, page 1080.