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:

No ECT, IAT, MAP, TP or VSS sensor DTCs set.
No IAC, linear EGR (pintle position) or transmission DTCs set.
Change in IAC less than 8 counts.
ECT greater than 158°F (69.8°C).
Vehicle speed greater than 25 MPH.
BARO greater than 70 kPa.
A/C clutch status unchanged.
Transmission locked/unlocked status unchanged.
No misfire DTC set.