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Well my engine was acting up in my 98 Mountaineer and from the forum posts it seemed like the MAF sensor (and this was what the check engine light indicated) was the problem. Well I bought a new one, put it in, and everything works fine, for a while, then the problem returns, engine bucking like it isn't getting any spark or fuel. The check engine stayed off for a bit but is now back on with the same code, I think it's 0401.....any suggestions.
I found all these P04XX codes, all refer to the EGR system. Could be a bad valve, sensor, or leak in the lines. I'd check all the basic stuff 1st, plugs wires, filters, etc if you haven't already done so. I went nuts for several weeks looking for the cause of a miss only to find a new plug was bad. Good luck...
P0400
Exhaust Gas Recirculation Flow Malfunction
P0401
Exhaust Gas Recirculation Flow Insufficient Detected
P0402
Exhaust Gas Recirculation Flow Excessive Detected
P0403
Exhaust Gas Recirculation Circuit Malfunction
P0404
Exhaust Gas Recirculation Circuit Range/Performance
P0405
Exhaust Gas Recirculation Sensor A Circuit Low
P0406
Exhaust Gas Recirculation Sensor A Circuit High
P0407
Exhaust Gas Recirculation Sensor B Circuit Low
Though I am usually caustious optimistic on Vic's advice - I would agree with him here and Bulldog. DPFE sensros are notorious on the late model X's. Notorious - like Jessie James or Billy the kid.