2002 Mercury Cougar service engine light EGR code

Tiny
JAYBIRDJR
  • MEMBER
  • 2002 MERCURY COUGAR
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 100,500 MILES
I have replaced egr valve, egr solenoid, egr pressure sensor, cleaned the intake plenum around the throttle body (had alot of carbon build up). The light with the same code has appeared again and again. I replaced the gas cap. Same code again. But there is no pressure when the gas cap is removed, most ford models have pressurized fuel tanks. Could this be the problem? What can I do to finally repair my wifes car?
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Sunday, May 3rd, 2009 AT 7:39 AM

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Tiny
RACEFAN966
  • EXPERT
Well I need to know what the P code is before I can be of much help. As for the tank having pressure not alway's true. My 95 F-150 no pressure when I remove the cap and my 98 Mustang same no pressure. So that is not alway's a tell tale sign ok. So if you would first get back to me with the code so I can look it up and see what all may be related to it and we will go from there.
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Wednesday, May 6th, 2009 AT 10:05 AM
Tiny
JAYBIRDJR
  • MEMBER
Code is p401 insufficent flow
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Wednesday, May 6th, 2009 AT 10:24 AM
Tiny
RACEFAN966
  • EXPERT
Ok this code is a little bit generic. It if insufficent flow but this could be for any number of reasons that it if setting this code. The egr system works with many other sensors. It works with the engine coolant temp sensor (ECT), the air intake temp sensor (IAT), throttle position sensor (TPS), mass air flow sensor (MAF), and the crank position sensor (CKP). The PCM uses all these sensors to determine how much egr flow is needed. So I would like to test these one at a time to determine if one or more of these sensor are bad. You will need a digital multi meter in order to do these tests. First I would like you to test the ECT and the IAT sensors. You simply unplug them and check the ohms of resistance of the sensors (not the wire harness). If you do this when the car is cold then get back to me with the ohms and the outside air temp at the time you tested them. Lets start here as these do go bad more frequently then the rest. You also may need to get some mass air flow cleaner (no other type will work) and clean the mass air flow meter. Anyway lets start with those sensors. Get back to me with what you find and we will take it from there. Here is a pic of the ECT first and then the IAT sensor.


http://www.2carpros.com/forum/automotive_pictures/249564_101777_1.jpg



IAT Sensor


http://www.2carpros.com/forum/automotive_pictures/249564_101610_1.jpg

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Thursday, May 7th, 2009 AT 10:05 AM

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