DTC P0401 Or DTC P0402: Condition

DTC P0401 is set when difference in intake manifold absolute pressure value when EGR valve is opened and when EGR valve is closed is less than predetermined. DTC P0402 is set when difference in intake manifold absolute pressure value when EGR valve is opened and when EGR valve is closed is greater than predetermined. MIL is illuminated when ECM (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are:

• EGR valve malfunction.
• EGR circuit malfunction.
• EGR system malfunction.
• Manifold Absolute Pressure (MAP) sensor malfunction.
• ECM (PCM) malfunction.