E048 Part 2 of 2

Diagnostic Chart.:

Wiring Diagram:

DESCRIPTION:

This diagnostic test monitors the oxygen sensor during a test period controlled by the PCM. When the EGR is off the oxygen sensor will detect a lean condition which will cause the integrator counts to increase. The counts must increase by 14 or more to check the flow rate of the valve. The EGR connector is located on the MAP sensor bracket behind the throttle body.

FAILURE CONDITIONS:

1. The PCM/ECM failed to detect an increase of 14 or more integrator counts, when EGR was commanded OFF.
2. System has failed test 3 times.

ACTION TAKEN:

1. PCM/ECM illuminates "SERVICE ENGINE SOON" telltale for entire key cycle.

NOTES ON FAULT TREE:

1. With engine idling, EGR solenoid should be energized. Test light across EGR solenoid terminals should be lit.

2. Checking for PCM's ability to turn solenoid off.



NOTE ON INTERMITTENTS:

At idle, manipulate the EGR solenoid connector and PCM/ECM connector and related wiring. The EGR solenoid should remain energized (CKT 435 grounded) to block vacuum to the EGR valve/vent vacuum to atmosphere. Listen for a change in idle quality.

Drive the car at TPS between 8 and 15 degrees and engine speed at 1450 to 1650 RPM to try and duplicate the code.

With a hot engine (idling), apply and release vacuum to the EGR valve to check for EGR valve binding in the up or down position.

Remove the EGR valve and check for excessive carbon build up that would restrict EGR flow or foreign materials holding the EGR valve open. Check for blocked or restricted EGR passage in the intake manifold reducing EGR flow.

Check vacuum hoses for pinched, cut, kinked, misrouted, or hoses blocked