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WARNING: This page is about a different car, the 1990 Cadillac Fleetwood and 1990 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
Code E52 is stored as an intermittent code and no lights are illuminated.
This code indicates that long-term memory in ECM has been reset. This will result whenever power is removed from ECM (disconnecting battery cables, disconnecting Blue ECM connector, etc.). Code should be cleared from memory after restoring ECM's power supply.
If Code E52 is seen accompanied by complaint of engine quit, stumble, lights flashing or other stored codes, check for intermittent loss of power or ground to ECM on circuits No. 439 and 450. Manipulate wiring and connections with engine running. Remove and replace ECM A/B, C/D and E/F connectors. Ensure they are latched.