I got an 0401 EGR Flow Insufficient last week. I cleared it and it showed up again after a couple of days. I replaced the EGR Valve and the 0401 reappeared. I replaced the DPFE and the code did not reappear. Great!
About a week later, I got an 0402 EGR Flow Excessive. Argh! New EGR Valve. New DPFE. The hoses to and from the DPFE to the tube look decent. They don't appear to have any build up inside.
Has anyone traced their 0401 or 0402 to the tube?
My first intinct is to replace the EGR valve again, assuming the one AutoZone gave me is stuck open. Is there any servicing I can do to it first? Like maybe soak it in carburator cleaner? Or spray it with WD-40?
Even though the Scorpio is not a North American vehicle, it nonetheless still uses the same exact EGR/DPFE system as that found on our Fords, so the information set forth is both accurate and relevant.
a 401 on a F150 is usually the ports clogged with carbon coming off the throttle body. You have to remove the throttle body, get at the ports with carb cleaner and coat hanger. Clean em' out good, and voila, no more 401 code.