401 code/EGR-Diagnosis suggestions?
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New User
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401 code/EGR-Diagnosis suggestions?
OK, so here is the story...About 10 months ago, my check engine light came on. I read the code and got 401:EGR flow insufficient. So I mess around with the EGR and it seems to be fine. I play with my multimeter for a while and decide that I need to replace the DPFE sensor. I replace the sensor and have the battery disconnected to clear the computer. When I started her up again it seemed fine and has been fine since.
Last week, my check engine light came on again. I get the code read and it is the same thing 401. I think it is highly improbable that the DPFE sensor is bad again in only 8 months. I used a vacuum pump and messed with the EGR and it seems to be working fine. The engine still runs fine but at times seems a little sputtery. No stalling at idle or on a cold start.
When I read the VREF on the harness side of the DPFE sensor it was not between 4-6 Volts. Any suggestions as to what I can test or look at next. I don't want to have to replace the PCM because that costs like $150.
Any help would be greatly appreciated. Thanks!!
Last week, my check engine light came on again. I get the code read and it is the same thing 401. I think it is highly improbable that the DPFE sensor is bad again in only 8 months. I used a vacuum pump and messed with the EGR and it seems to be working fine. The engine still runs fine but at times seems a little sputtery. No stalling at idle or on a cold start.
When I read the VREF on the harness side of the DPFE sensor it was not between 4-6 Volts. Any suggestions as to what I can test or look at next. I don't want to have to replace the PCM because that costs like $150.
Any help would be greatly appreciated. Thanks!!
Elder User
Joined: Feb 2004
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Highly unlikely it's the pcm, The sensor, or plugged ports yes. However, vref should be around 5 volts, if not, check the wiring to the sensor all it needs is a little voltage drop. Ohming the wire isn't good enough either, check voltage drop. What was vref reading?
Post Fiend
Joined: Jan 2003
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From: Connecticut
Here's a couple of great resources regarding Ford DPFE/EGR System Operation & Testing:
http://www.tomco-inc.com/Tech_Tips/ttt35.pdf
http://www.tomco-inc.com/Tech_Tips/ttt36.pdf
http://www.tomco-inc.com/Tech_Tips/ttt35.pdf
http://www.tomco-inc.com/Tech_Tips/ttt36.pdf
Post Fiend
Joined: Jan 2003
Posts: 9,748
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From: Connecticut
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Joined: Aug 2007
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Puzzled...
Ok here is a silly question. I have a 98 Ranger and unfortunately, my Haynes manual is 94-97, it shows that while looking at the DPFE sensor, with the plug on the right, the top pin of the three is the VREF. However, in the sources that you have posted here, Tomco Techtips and your website it shows that the bottom pin is the VREF. I have been testing the top... Well, I am at work right now and don't have my multimeter so I can't go check it right now. Am I correct to assume that the bottom pin is the correct one for testing VREF?
