Service Engine soon

[brmface]

Hello!!! I have a 2002 Mustang, 3.8L, Auto, 85,500 miles. The other day I ran the Air for a while, and got the dreaded "SERVICE ENGINE SOON" warning light. I went down to Auto Zone and had it tested, the DTCS was P0401 (EGR Flow Insufficient). I replaced the EGR Valve, and cleared the computer (disconnecting the ( - )pole of the battery, and pumping the brakes a few times). leaving off for 30 mins. Took it for a ride, and it went on again after about 10 miles. I went back to Auto Zone and had it tested got the P0401 again!! Then I replaced the EGR Sensor, cleared the computer, and it went away. I drove it for about 125 miles, I used the " TRAC OFF" option, and the warning light came on again!!! Since then I have cleared the computer, and it runs clean. I just want to know what is happening here?
Did I have to replace the 2 EGR parts, or is there something else wrong?? Something maybe about the voltage?? I don't know???? Anyone have a clue??? I have the feeling if I use the air, or TRAC OFF, that it is going to come back. Thanks, BRM

 

[Blown331LX]

This humors me..."pumping the brakes" has no effect at all on resetting the computer, your trac buttons dont have any effect on performance or check engine lights either. The A/C being on had no connection what so ever with the P0401. An EGR system is only commanded on by the computer during highway driving. the computer sends a signal to the electric valve, this valve has vaccuum going to it at all times, when it sees the on signal from the computer it opens a diaphram and this alows the egr gas to be recirculated in the motor. A DPFE sensor tells the computer how much this system is working. This is the sensors that always gets replaced by us at the dealer cause it causes the most problems. And lets clarify something a code reader at advanced does not tell you what the problem is, it ONLY tells you what system has a fault to cause the light to come on. You did not need a EGR valve but prolly just the sensor, this is why people thake it to a shop and pay a diagnostic, CHEAP people go waste money on THROWING parts at a code that Autozone gave them cause the believe some pimpled face prick behind the counter that knows nothing about cars, just how to sell you parts. The only thing you need to do to clear the code is dissconnect the battery, or use the CLEAR CODES function on the code reader. And lastly Ive seen carbon build up in the EGR ports, hoses, and intake be the leading cause to egr codes on Fords, all you have to do is find the blockage clean it and reassemble, no parts needed.

 

[stang8urimport]

Insuffeciant EGR flow is almost ALWAYS the DPFE sensor. Very very common on all Fords equipt with the sensor.

And I completely agree with the last post. I get this crap all day long at my shop... "Autozone diags for free" hahahahah. I always tell them, they tell you what the code says and attempts to sell you parts that MIGHT fix the problem. You pay me 60 bucks to tell you what the PROBLEM is, not just a code. It's all a sales game.

 

[brmface]

Thanks for the feedback!! By Pumping the breaks, (I was told) this would clear all the power left in the computer, just like those old TV sets with picture tubs, after you unplug them, the tube still retains power to it and could give you a nice shock if you start poking around...Makes sense. So answer this one...because I want to learn..is the DPFE sensor the same thing as the EGR sensor that I replaced, or is that a different sensor???
And, CHEAP is like having someone like you for a neighbor, and me coming over and having you fix it for free (and not giving you a 6-pack!!!)...brm

 

[brmface]

I also found this to be helpful!!!
These links have information on EGR valve, and a troubleshooting.
http://www.kemparts.com/techtalk/tt12.asp
http://www.kemparts.com/techtalk/tt02.asp

 

[Blown331LX]

Who ever told you to pump brakes to help clear a computer did that to laugh at you, Im glad they did cause I got a kick out of it. The DPFE sensor on you car should be a black plastic box about 1.5 x 2.5" and 1/4" thick. It should have a 3 wire connector on it and 2 small vaccum hoses, one side hose on the box should read "HI" the other "REF". If this is not what you have replaced you need to get one and replace it. What u should really do to verify you have no carbon build up is to pull vaccum on the EGR valve with a manual pump and engine running. If the car stumbles and or cuts off then the EGR system is working, and then put a DPFE on there. If it doesnt stumble or cut off take it to someone who can properly diagnois it instead of wasting money on parts you dont need. The price you paid for the EGR sensor you installed and didnt need would have more than covered a diagnostic charge. Good Luck

 

[brmface]

Well now I am looking at an other possible problem. The EVR Solenoid...when I unplug the power to it, the hose going to the EGR valve still has vacuum???? This is telling me that it is running all the time...what you think????