Circuit Description

This test checks if EGR valve is stuck open. VCM determines that EGR is stuck open if actual EGR position and learned closed EGR position vary by more than a predetermined value. VCM checks for a stuck valve when desired EGR position is at zero percent. VCM commands EGR valve to 100 percent during certain driving conditions in order to clear a possible restriction from EGR valve if VCM determines that valve is stuck open.

PCM rechecks for a stuck valve when desired EGR position returns to zero percent. A failure timer increments if the stuck EGR valve condition is still present. This DTC sets when timer reaches a predetermined value.

Conditions for setting DTC:

• ECT greater than 176°F (80°C) but less than 248°F (120°C).
• IAT less than 212°F (100°C).
• Desired EGR greater than 14 percent.
• Difference between actual and learned EGR pintle position greater than 0.2 volt.