Note On Intermittents

WARNING: This page is about a different car, the 1993 Cadillac Seville and 1993 Cadillac Eldorado. However, it is still accessible from the selected car via links, so may be relevant.

With engine at idle, manipulate EGR solenoid connector and related wiring. Listen for a change in idle quality. Drive vehicle with throttle angle at 8-15 degrees and engine at 1450-1650 RPM to try to duplicate code. Remove EGR valve, and check it for carbon build-up which would restrict EGR flow and for foreign materials holding EGR valve open. Check for pinched, cut, kinked, misrouted or blocked vacuum passages and/or vacuum hoses reducing EGR flow. Check for EGR valve binding in up or down position.

Fig 1: PCM Code P048 Schematic - EGR System Fault

Courtesy of GENERAL MOTORS CORP.

Fig 2: PCM Code P048 Flow Chart (1 Of 2) - EGR System Fault

Courtesy of GENERAL MOTORS CORP.

Fig 3: PCM Code P048 Flow Chart (2 Of 2) - EGR System Fault

Courtesy of GENERAL MOTORS CORP.