Circuit Description
The Engine Control Module (ECM) calculates a calibration memory checksum based on the values of certain parameters in the ECM. This checksum is compared to an expected value in the ECM to detect tampering.

Component Location
The ECM mounting location varies, depending on the engine model, and may be mounted either on or off the engine.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes
The Engine Control Module (ECM) detected the calibration memory checksum did not match the expected value or it did not complete before ECM shutdown.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
Conditions for Clearing the Fault Code
In order for this fault code to go inactive, a calibration download is necessary.

The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.

Shop Talk
Possible causes of this fault code include:

Malfunctioning ECM software

Tampering of the ECM software

Possible Cause:
1) N/A