Circuit Description

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

Conditions required to set DTC are:

• No CKP, ECT, EGR pintle position, IAT, MAP, or TP sensor DTCs set.
• No misfire or VSS DTCs set.
• BARO is greater than 70 kPa.
• ECT greater than 167°F (75°C).
• Engine speed is 800-1200 RPM.
• IAC position steady.
• Vehicle speed greater than 25 MPH.
• TP angle less than one percent.
• Commanded state of A/C relay is steady.
• MAP changes monitored during EGR flow test indicate insufficient EGR flow.