I need some help here. My CEL came on a couple weeks ago. I went to Advance Auto to have them scan it to find out what code it was. P0401 came up which is EGR valve, insufficient flow detected. I replaced the EGR valve. The next day the CEL came back on. So I bought a EGR solenoid replaced that. The CEL came back on tonight. Can anyone give me any ideas as to what to do next. BTW I have an 02 4.0 XLT Thanks for your help.

 

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Have you had the code checked again to make sure that it's coming on for the same thing or possibly something else?

 

Thanks for the info guys. I went and put a DPFE sensor on 2 days ago and the CEL hasn't come back on. I also talked to me mechanic and he told me from his experience the DPFE sensor is more like to be the problem than the EGR valve or the EGR solenoid.