I have a 2002 Axiom. A check engine light came on and the code is P0401 (EGR Insufficient flow detected). My mechanic changed the EGR, but the check engine came back on with the same P0401 code.
The next step, my mechanic changed the intake manifold (used) and the MAP sensor. But again, the check engine came back with the same P0401 code. Does anyone have any suggestion to fix this
P0401 code?

 

Start by finding a competent mechanic that troubleshoots. Your guy is throwing parts at it.

This code is as the description suggests. The EGR is working however the volume of EGR gasses is lower than the ECM predicted. The first step in proper troubleshooting procedures for this DTC is to perform a exhaust pressure test.