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  1. #1
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    GM 3100 Check Engine Light P0401 - EGR problem

    I have a 1996 Regal with the 3100 V6 that has a check engine light. The code is P0401. I have replaced the EGR with a working one from a low mileage car. The light is still on. What should I check next? How can I be sure the new EGR works or my old one is bad? From what I can see on this engine the only parts of the EGR system is the valve itself and the pipe that goes from the intake to the exhaust manifold.

    My next step is to soak the bottom of the EGR valve in carb cleaner and spray it down that tube as well.
    1991 Cutlass Supreme 3.1L 109k<br />

  2. #2
    Guy Incognito WhatTheFehl's Avatar
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    Mike F

    1999 Pontiac Grand Prix GTP - 195,000 miles, SD headers, FWI, Toy/Money Pit
    . Car of the Quarter 2nd quarter 2013
    2004 Subaru Outback Wagon - 138,000 miles, 2.5 H4 EJ251, Tsudo headers, HID fogs, DD

  3. #3
    Guy Incognito WhatTheFehl's Avatar
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    Follow the steps to that video. A few cautions:

    -You will definitely need a new throttle body gasket, chances are your old one will disintegrate when you remove the throttle body.
    -Make sure you install the new gasket properly. I installed mine apparently backwards, and it caused a massive leak after the throttle body which caused the engine to rev straight up to the rev limiter as soon as it was started. Readjusting the gasket solved this.
    -There is a coolant pipe that runs right in front of the lower throttle body bolt. It is a pain in the ass to remove, but it can be done with regular tools, some time, and some swearing.
    -You will need LOTS AND LOTS of carburetor cleaner and shop rags.
    -Compressed air also helps for cleaning the top of the EGR passage.
    -The video recommends using a cut piece of speedometer cable for cleaning the port. I used a leftover piece of brake cable from when my dad fixed the parking brake on our van. It worked just as well.
    -The video also shows installing the cable in the drill and plunging it down through the EGR port into the intake plenum. I found it was easier to do the opposite, force the piece of cable through the port from the plenum side into the EGR passage. It is easier to get to and went straight through, the port is pretty difficult to see from the EGR passage.
    -A piece of wire coat hanger is your friend.\

    Also the EGR test cycle on your car is around 45-50 mph or more, in D, when the engine is not under a load. You will hear a puttering then the light should come on for the EGR. I'm not 100% sure if this is the same on your OBD2 car as mine has OBD1.5. But a sure fire way to turn my SES light on before I cleaned the port was to drive on the highway.
    Last edited by WhatTheFehl; 06-11-2010 at 11:49 AM.
    Mike F

    1999 Pontiac Grand Prix GTP - 195,000 miles, SD headers, FWI, Toy/Money Pit
    . Car of the Quarter 2nd quarter 2013
    2004 Subaru Outback Wagon - 138,000 miles, 2.5 H4 EJ251, Tsudo headers, HID fogs, DD

  4. #4
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    Thanks for that video, it really helped.

    I did the work but now how do I clear the code to see if it comes back?
    1991 Cutlass Supreme 3.1L 109k<br />

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    Guy Incognito WhatTheFehl's Avatar
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    If you have a scantool, hook it up and clear the codes. Or take it to PepBoys and they will scan your codes and clear them for free. You could also try disconnecting the negative battery terminal for a few minutes and then hooking it back up. That usually cleared codes for mine, but once again, I have OBD1.5 and you have OBD2 so I'm not sure if this will work for you. By the way, when you first start it after hooking everything back up (battery, TPS, IAC, etc) it may stall immediately. That's just the TPS and/or the IAC resetting itself.
    Mike F

    1999 Pontiac Grand Prix GTP - 195,000 miles, SD headers, FWI, Toy/Money Pit
    . Car of the Quarter 2nd quarter 2013
    2004 Subaru Outback Wagon - 138,000 miles, 2.5 H4 EJ251, Tsudo headers, HID fogs, DD

  6. #6
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    It started right up and didn't stall. My local Autozone won't clear the code for me, just read it. They tell me "im not supposed to". I can't drive as far as pep boys the car is not registered and I have enough money into it I don't want to pay impound fees. I will try disconnecting the battery. I had it disconnected during the cleaning but I started the car with the EGR unplugged. Back outside.
    1991 Cutlass Supreme 3.1L 109k<br />

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    Arrive Alive tornado_735's Avatar
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    Yes unhooking the battery will clear the codes on any car. And you only have to have it unhooked for about 10 seconds.

    2006 Pontiac Grand Prix - 109k
    1995 Range Rover 4.0SE V8 - 121k
    1993 Range Rover County LWB 4.2L V8 - 151k
    "...then I saw that there was a way to Hell, even from the gates of Heaven..."

  8. #8
    Arrive Alive tornado_735's Avatar
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    Oh, and you yourself are allowed to clear the codes with the scantool.

    2006 Pontiac Grand Prix - 109k
    1995 Range Rover 4.0SE V8 - 121k
    1993 Range Rover County LWB 4.2L V8 - 151k
    "...then I saw that there was a way to Hell, even from the gates of Heaven..."

  9. #9
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    I left the battery unhooked for about 30 minutes before reconnecting it. Started the car, check engine light still on.
    1991 Cutlass Supreme 3.1L 109k<br />

  10. #10
    Arrive Alive tornado_735's Avatar
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    Then you got something else going on.

    2006 Pontiac Grand Prix - 109k
    1995 Range Rover 4.0SE V8 - 121k
    1993 Range Rover County LWB 4.2L V8 - 151k
    "...then I saw that there was a way to Hell, even from the gates of Heaven..."

  11. #11
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    I also have a loose wire, can't find a place for it. Can someone identify it for me, thanks.

    I have a feeling it may have been for the Dynaride which I think has been removed?

    1991 Cutlass Supreme 3.1L 109k<br />

  12. #12
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    Quote Originally Posted by tornado_735 View Post
    Then you got something else going on.
    The only code that came up yesterday was for the EGR. I'm pretty sure there is nothing else at fault for this light. Unless the EGR is no good. Unfortunately I don't have a 9v battery and wires to test it.
    1991 Cutlass Supreme 3.1L 109k<br />

  13. #13
    RobertISaar's Avatar
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    do you have an underhood light?
    King of Code
    1995 Monte Carlo LS 3100, 4T60E... for now, future plans include driving it until the wheels fall off!



  14. #14
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    aha! that has to be it haha im so stupid
    1991 Cutlass Supreme 3.1L 109k<br />

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    RobertISaar's Avatar
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    sometimes, the simplest answer is the correct one.
    King of Code
    1995 Monte Carlo LS 3100, 4T60E... for now, future plans include driving it until the wheels fall off!



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