Hi,

I own a 2001 Expy with the 4.6 and about 44,000 miles. I recently got a "Service Engine Soon" light that came on. From what I have read on this site, and from what Autozone has told me after scanning the code (PO402), it means that I have "Excessive EGR at Idle". I have learned that it can be 1 (or more) of three things that can cause this condition:

1) Bad EGR valve
2) Bad Solenoid
3) Bad DPFE sensor

I have cleaned and tested the EGR valve. It appears ok. I have tested the solenoid. It is within the specified limits. The DPFE sensor is another story though. I can not seem to locate it on my truck. According to my repair manual, it's suppose to be mounted on a bracket which is attached to the throttle body. It is suppose to be metal (or plastic) and probably about 4 x 6 inches with a hose attached to it. Well, the bracket is there but no sensor. What I do see, however, is a smaller sensor, about 1 x 2 inches, that has 2 small hoses (maybe 1/4 inch diameter) attached to it along with a wiring harness. The hoses that are attached to it come from the steel exhaust tube that goes from the exhaust pipe to the EGR valve. It is not physically mounted to anything. It's location is near the firewall, not on the throttle body. I'm assuming that this is the DPFE sensor?? Does anyone else have this same setup or problem? How do I test this sensor and what should it's specifications be? Also, I don't suspect that I have "clogged" EGR ports because my code is for "Excessive EGR at Idle", right? Somebody please help. I had reset the computer after conducting my tests and the SES light remained off more about 10 miles. Unfortunately it came back on.


My other problem has existed for some time. I feel a horrible missfire when accelerating heavily off the line. If I bury the accelerator though, I don't feel it. Likewise, if I accelerate normally, I also do not feel the missfire. I get NO Service Engine light that comes on. I had the vehicle diagnosed at Ford about 5 months ago and they told me it was the #3 coil pack. I replaced it myself and it fixed the problem for a few weeks or so. It has come back again. I recently bought 2 more new coil packs ($57.00 each) and put them in. I've tried swapping out each of the packs 2 at a time and then test driving the vehicle each time hoping that I find the bad pack(s). I'm very close to just replacing all of the old packs with new ones and saying the "heck with it". Only problem is that it's an expensive fix. Anybody got any suggestions? BTW, my spark plugs are about 5 months old. I replaced them with Bosch Platinums when I originally got the missfire the first time.

Thanks,

Anthony Tsiouklas
Dunedin, Florida

 

It sounds like you may have found it. A prior thread also stated that 95% of the p0402 codes are caused by faulty DPFE sensors ...

https://www.f150online.com/forums/sh...fe+picture+4.6

 

Thanks Temp1! I took a ride to the Ford dealership and took a look at the DPFE sensor that they stock. My suspision was correct; the original DPFE sensor, which used to mount to the throttle body, has been replaced by a much smaller unit that is not physically mounted to anything except 2 hoses that protrude from the EGR pipe that goes to the EGR valve. It's also costs about 1/2 the price ($30.00) of the original. I guess mine has already been replaced once before by the previous owner because the original mounting bracket still exists. I bought the sensor and replaced the sensor then reset my Service Engine Soon light. I drove it for about 10 miles last night and the loght has not come on yet. Hopefully this fixes it. Just an FYI: the guy behind the parts counter said that the DPFE sensor often go bad. Thanks again!

Anthony