Note on Intermittents
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.
If intermittent Code E20 is stored, unplug oil pressure switch, start engine and allow to idle. Manipulate affected wiring, ensure ECM P1 (C/D) connector is latched and check relay for proper installation into relay center socket. If fault is induced, engine will stall. Code E20 will set. If Code E20 sets without engine stalling, cause is intermittent open in circuit No. 120 between ECM pin E13 and splice to fuel pump relay.