DTC P0401 Or DTC P0402: Condition

DTC is set when during deceleration (engine speed high with closed throttle switch on) in which fuel cut is involved. The difference in intake manifold absolute pressure between when EGR valve is opened and when it is closed is larger or smaller than specified value. ECM monitors this circuit once per drive cycle. MIL is illuminated when Engine Control Module (ECM) detects malfunction during 2 consecutive drive cycles. Possible causes are:

• EGR valve malfunction.
• EGR circuit malfunction.
• EGR passage restricted.
• ECM malfunction.