[QUOTE=Cooby]So two weeks ago I took my mountaineer to the dealer for it's 90K service. Along with the regular service they said i had an exhaust leak and I told them to fix it.
Then last week I moved and drove the truck about 600 miles loaded down pretty good with stuff. About halfway through the trip I noticed when I stepped on the gas it would make a kind of clattering noise in time with he acceleration. When I reached my destination, parked the car, and later restarted it, the check engine light came on and has been on ever since.
I took it to Autozone and hooked up the OBD unit and it said it came back with two codes: P1405 and P1405 with a "PD". I know P1405 is "DPFE sensor upstream hose off or plugged". I don't know what the "PD" means. And the noise the car is making could very well be the sound of a slightly unmuffled engine.
Easiest check first:
DTC P1405-Differential Pressure
Feedback Electronic (DPFE) sensor upstream hose off
or plugged - or cracked
I believe it is on the driver's side of engine, half-way down... also, ck all hoses for damage or "left-off during lunch break"
more DTC info below