1997 Mercury Mountaineer
Transmission: Automatic
Fuel: Gasoline
Cylinders: 8 Drivetrain: AWD
Engine: 5.0L V8
OBDII CODE: P0402
MILEAGE: 200,000

Does anyone have any suggestions?

 

Check the EGR valve operation and the DPFE. Prob. the DPFE, very common failure. The hoses that feed it clog as well.

 

My turn to battle this P0402 EGR Flow Excessive code...

Found all the great threads (thanks all!) and tested the EGR valve by applying a little vacuum as instructed - engine went to a rough idle and recovered when vacuum was released which seems to indicate the valve is fine.

One of the great threads argues that the P0402 code can't be the DPFE sensor, so I'm confused by the other threads that say just replace it.

Thoughts?

Also, where exactly are the places to check for clogging? Can't say I see any "elbows" ?!? ('98 F150 SC 5.4l FS/SB OffRoad w/70k miles)

Thanks in advance,

 

Replace the DPFE sensor with a Motorcraft (only) unit, reset the PCM, and retest.

Steve