Circuit Description

PCM directly controls the ground for the linear EGR valve when certain conditions have been met. Ignition voltage is supplied to EGR valve when ignition is turned on. When PCM grounds the EGR valve, a diagnostic feedback signal can determine if valve had actually moved.

EGR flow restrictions are diagnosed during a deceleration. EGR valve is commanded closed during normal deceleration and a change in MAP is expected. If the change in MAP is less than a threshold, a restricted flow is indicated.

DTC will set if calculated value compared to an engine speed barometric pressure determines that there is restriction in EGR flow when engine speed is 1250-2600 RPM, VSS is greater than 35 MPH, transaxle in top gear, ECT is greater than 150°F (70°C) and no CKP, EGR, TP sensor, MAP, VSS, IAT, ECT or IAC DTCs have been set. EGR flow insufficient test is checked once per ignition cycle during deceleration.