Circuit Description

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

Conditions required to set DTC are:

• No TP, VSS, EVAP, IAC, IAT, MAP, ECT or excessive EGR DTCs set.
• BARO is greater than 72 kPa.
• Engine coolant temperature is greater than 165°F (74°C).
• System voltage is 11.5-16 volts.
• Vehicle speed is greater than 18 MPH.
• IAC position is steady, changing less than 5 counts.
• A/C clutch status is unchanged.