DTC P0402: EGR System, Excessive Flow: Condition

DTC is set when the difference in intake manifold pressures between open EGR and closed EGR is too large. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are:

• EGR valve base gasket damaged or missing.
• PCM malfunction.