Trouble codes

[scrutton]

I have the following trouble code come up on my 96 Explorer sport (146K miles):-

P0401 - Exhaust Gas Recirculation Flow Insufficient detected
P0402 - Exhaust Gas Recirculation Flow Excessive detected
P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

I recently took my vehicle by the dealer, they checked the codes and recommmended that the DPFE sensor be replaced.

I've called a few places to seek quotes on getting the cat converter replaced - I meet a healthy dose of skepticism when enquiring about this - they claim that unless I can hear stuff rattling around inside it, or my top speed is limited to 30 mph or so (and neither symptom is present), there's probably nothing wrong with the converter.

Any suggestions from you folks out there. Does changing the DPFE sensor sound like it may be the right thing to do?

Thanks,

Paul Scrutton

 

[Alec]

I don't know exactly what that sensor does, but I have a feeling that's the sensor inside your first cat. The codes cite trouble with the EGR and the cat, but I don't think the cat is the problem. If that's all that your dealer recommended, then I say go for it and replace the sensor. You can probably do it yourself, as it's right under the truck. Since you have a 96, it's probably not that your cat is bad. Another thing that popped into my head: have you had your fuel injectors flushed recently? With 150K miles, you probably have carbon buildups in your systems and should probably get this done, or run an injector cleaner in your fuel for the next few fill-ups.

 

[Robert]

No, it has nothing to do with your catalytic converter. The good news is that the DPFE should be significantly cheaper and much easier to replace. On my SOHC it is a small black box about 3" X 2" mounted to the fender side of my driver's side valve cover. It has two vacuum lines connected to it and one electrical connector. Its purpose is to measure the differential pressure between two sources. It should be a 10 minute swap. If that is what the dealer is suggesting, that is where I would start. Of course dealers have been wrong before. I'm fighting with mine now while I drive a Taurus

 

[kps36]

Robert is exactly right. But I think Ford calls it the EGr Vacuum Regulator, the description was right on. My search in town turned out that it is a Dealer-only part...$76.83.
That should fix your problem. Check in chapter 6 of the Haynes for reference. Mine doesn;t show a picture, but how to check it (if you can understand it???).

 

[Alec]

Ok, sorry. I tried.