The P0603 code in your 2023 Chevrolet Silverado indicates a keep alive memory (KAM) error in the engine control module (ECM). Keep alive memory stores learned values that help the ECM optimize engine performance for your specific driving patterns and conditions. When this memory is lost or corrupted, the ECM sets P0603 and loses its adaptive learning data.
Understanding Keep Alive Memory
Your Silverado's ECM continuously learns and stores adjustments for fuel trim, idle speed, and various operating parameters. This data, stored in volatile memory, requires constant battery power to maintain. When power is interrupted, this learned data is lost. The ECM expects certain memory integrity checks to pass; when they fail, P0603 is triggered.
Common Causes in 2023 Silverados
Battery disconnection or replacement is the most common trigger, especially if proper relearn procedures aren't followed. Parasitic draws that drain the battery overnight can corrupt KAM. Corroded battery terminals or loose connections cause intermittent power loss to the ECM. In some cases, the ECM's internal backup power circuit fails, preventing proper memory retention.
Symptoms and Concerns
After the KAM is lost, your Silverado may exhibit rough idle, hesitation, or poor fuel economy until it relearns proper values. The check engine light illuminates, and you may notice the transmission shifting differently as it loses its learned shift points. These symptoms typically improve as the vehicle relearns driving patterns over 50-100 miles.
Diagnostic and Repair Steps
Check battery health and terminal connections first. Measure parasitic draw with the vehicle off; more than 50 milliamps after modules sleep indicates a problem. Verify the ECM grounds are clean and tight. Clear the code and drive the vehicle to see if it relearns properly. If P0603 returns despite good battery conditions, the ECM may need replacement.