1995 Taurus Wagon

[sanjoh]

Hi,
My husband's wagon just died on the highway yesterday. Today he had it in a garage running diagnostics as it will not start. They say it is showing up as the PFE sensor and this is about $200. They cannot guarantee this is the problem but they say they need to replace this in order to start the car to establish the problem! I for see a huge bill!!

Would this sensor cause the car to stop dead??

He has never had any problems with the car in the past, no starting probs nothing..any help appreciated.

Thanks
Sandra

[TaurusKing]

I'm not an expert on cars that stop dead in the middle of the road, but I don't believe the pfe sensor would cause that, of course anything is possible the pfe sensor uses exhaust pressure, converts it to voltage which the pcm uses to modulate the operation of the egr system, sort of a simple explanation.. it's possible one of the egr parts is creating a huge vacuum leak which might cause the car to stall, should be able to hear it though,, as an aside, the pfe sensor on my 94 wagon, 3.0, had a small crack in the short rubber hose, no check engine light, no problems with starting, running, I happened to find it when I replaced the pvc valve which sits there next to the pfe sensor,, not only that, a code had been set in the continous memory which pointed to the pfe sensor, I replaced it, cost $40 at the parts store the old obdI systems won't necessarily set the light unless there's total failure of a monitored part, even though possibly a code might be set in the continous memory... If you're planning on keeping the car, I suggest you buy a little code reader, usually around $30 or so, not a fix-all know-all, but nice to have to use once in a while to check that all is relatively well.

[TaurusKing]

An addendum to above, they have checked fuel pressure?? Fine?? My 87 died in the road, only car that ever did it to me, it was the fuel pump.. ignition parts??? I don't know, I think most of the pcm's and related electronic distributor parts are pretty reliable, at least in my experience..

[shorod]

Sounds like they may be referring to the DPFE sensor, Differential Pressure Feedback E(something that escapes me now) sensor which is a common part to fail. This part feedsback the position of the EGR valve to the computer, which the computer uses to tell the EGR to open or close more. Do some searches on this forum for the DPFE, sounds like an easy part to replace and something you can pick up for around $60, but the tow bill to get it back home to do it yourself may come out to about the same as what they want to charge.

If they are really suspecting the DPFE sensor, they should be able to just disconnect and plug the vacuum to the EGR valve so the PCM cannot tell the EGR valve to open. If the DPFE is the problem, this will take it out of the loop that might cause a no-start. During start up, the EGR valve should be closed, and yours should close with no vacuum applied, so it would be closed anyway when trying to start the car. If the car still won't start, the DPFE may not be the problem.

You may have a stuck EGR valve contributing to the no-start condition. A piece of carbon may be lodged in the pintle valve of the EGR valve, preventing it from closing fully at idle.

What is not happening when you try to start the car? There are checks the shop should do before replacing parts that the computer diagnostics says are bad. For example, does the car have spark and fuel? The DPFE will have nothing to do with no spark or fuel. If the EGR is not closed during a startup condition, the EGR should be removed and checked. The DPFE by itself will not cause the EGR to be open during startup.

My non-expert opinion is they should get the car started BEFORE replacing the DPFE.

-Rod

[sanjoh]

Thank you.

Luckily they did some more tests before ordering the sensor. They discovered the catalytic converter was bunged up and something had blown through the exhaust. They replaced the converter and the exhaust and the car runs well. (cost $600 )

Hubby picked it up on Thursday night and on Friday the check engine light started coming on. It comes on then goes off.. will have to take it back to the garage.. wondering now if this is from the sensor..?

Again thank you, we appreciate your kind help.

[shorod]

Could be, but obviously the sensor would not have fixed the real problem.

Since you are posting on this forum, I assume you have the desire to be an educated consumer. Therefore, I suggest you swing by a local auto parts store. Most (and just about all the chain stores) will read the codes from the computer at no charge. Mention to them that you do not wish to have the codes cleared yet, you just want to know what they are.

Post the codes back here (preferrably the code numbers) and someone should be able to give you some direction on what likely causes are.

-Rod

[way2old]

Agree with you there Rod. If the exact code numbers are posted, not what they tell you is wrong, it is easier to research and give you a good answer. Yhe code should be something like P0401 or a P0xxx where x equals numbers.