Circuit Description

WARNING: This page is about a different car, the 2000 Isuzu Hombre. However, it is still accessible from the selected car via links, so may be relevant.

Vehicle Control Module (VCM) tests Exhaust Gas Recirculation (EGR) valve by momentarily commanding valve open while monitoring engine MAP. VCM will illuminate MIL and store DTC P0401 if expected increase is not seen under certain conditions during deceleration.

Conditions required to set DTC are:

DTCs P0300, P1336 or P1404 are not set.
No ECT, IAC, IAT, MAP or TP sensor DTCs set.
Ignition voltage greater than 11.7 volts.
EGR commanded ON (Open). Desired pintle position greater than zero percent.
Actual pintle position differs from desired position by greater than 9 percent for 18 seconds.