Another CEL problem
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.