DTC P0401: EGR System, Insufficient Flow: Condition
WARNING: This page is about a different car, the 2002 Mazda Protege5 and 2002 Mazda Protege. However, it is still accessible from the selected car via links, so may be relevant.
DTC is set when the difference in intake manifold pressure between open EGR and closed EGR is too small. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are:
- EGR valve malfunction.
- EGR boost sensor malfunction.
- EGR boost sensor solenoid valve malfunction.
- EGR valve base gasket malfunction.
- PCM malfunction.