PCM code P 0446
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Cadillac DeVille 1985 to 2005 including:
1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, PCM code P 0446 in Past Cadillac Vehicle Discussion; Just had fuel pump replaced in 2004 Cadillac Deville DTS and am going to replace the intake plenum in a ...
  1. #1
    Otten33 is offline Cadillac Owners Member
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    PCM code P 0446

    Just had fuel pump replaced in 2004 Cadillac Deville DTS and am going to replace the intake plenum in a couple of days because of the PCM 0171 & 0174 codes I was receiving. My fuel gauge was also becoming erratic when down to a quarter of a tank. After replacing the fuel pump I received a PCM P0446. Any advice? Thanks.

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  3. #2
    Otten33 is offline Cadillac Owners Member
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    Re: Pcm p0446

    Cleared the codes and it hasn't come back yet.

  4. #3
    Otten33 is offline Cadillac Owners Member
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    Re: PCM code P 0446

    P0446 code came back last night. Is this the fuel pressure sensor on the fuel tank that could be causing this?

  5. #4
    Submariner409's Avatar
    Submariner409 is offline If it won't run, chrome it
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    Re: PCM code P 0446

    Always post code definitions - we don't have the several hundred codes memorized - yet.

    http://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

  6. #5
    Otten33 is offline Cadillac Owners Member
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    Re: PCM code P 0446

    Sorry. That makes sense! I think this is being caused by the new aftermarket fuel pump I had put on. My mechanic said that the orginal fuel pump had a different set up for the FTP than the new fuel pump. Any ideas?

  7. #6
    amunderdog is offline Cadillac Owners Enthusiast
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    Re: PCM code P 0446

    P0446 code came back last night.
    DTC P0446 EVAP Vent Solenoid Valve Control System

  8. #7
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: PCM code P 0446

    Probably a bad solenoid.

  9. #8
    Otten33 is offline Cadillac Owners Member
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    Re: PCM code P 0446

    What type of bad solenoid?

  10. #9
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: PCM code P 0446

    The EVAP canister vent solenoid, #29.

    http://www.gmpartsgiant.com/Page_Pro...PartSortBy=Key

  11. #10
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    trailor is offline Cadillac Owners Fanatic
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    This code is a mystery. I've replaced both the solenoid and the damn sensor/purge valve and it's still pulls the code.

  12. #11
    Otten33 is offline Cadillac Owners Member
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    Re: PCM code P 0446

    I am in the same boat. I just replaced purge and vent solenoids. Still get codes. I still think this may be caused by that aftermarket fuel pump. The new fuel pump doesn't read exactly the same as the factory one. It is off by probably 1/2 to 3/4 of a gallon so not bad. The price was like $70 compared to $275 for the acdelco. For the price I can live with the slightly off gas gauge. That being said, I read somewhere that the solenoid could be reading that there is more gas than their really is in the tank therefore the vapor level is off. This difference is possibly causing the PCM 0446 code. I am not an expert with cars so I think I wrote that correctly. Anyone got ideas or is there other things I can check before just having to live with this code. By the way car drives great and is much more responsive since replacing both solenoids.

  13. #12
    Otten33 is offline Cadillac Owners Member
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    Re: PCM code P 0446

    Any ideas would be appreciated.

  14. #13
    DTECKBAUER is offline Cadillac Owners Member
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    Re: PCM code P 0446

    i had that code and found a broken wire going in to part 33 on that diagram. fixed that and my code went away

  15. #14
    70cougar is offline Cadillac Owners Enthusiast
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    Re: PCM code P 0446

    I've never had this particular DTC, but I just checked my 02 FSM. It says to first check operation of vent valve (you did that by replacing it).

    Then it says to check for blocked vent valve line - you can disconnect it and see if it is clogged.

    If that isn't it, it says to check the electrical connections to the fuel tank pressure (FTP) sensor that is inside the fuel tank accessible by the access panel in the trunk. It's possible these wires were disturbed when your fuel pump was put in.

    If that's not it, it then says to use a Tech II scan tool to check the operation of the sensor. If you don't have access to a Tech II, you could try replacing the sensor (don't know the cost of one).

    Keep in mind that after you clear this code, the test for it only runs under certain specific conditions, so the code may not come right back after clearing even if not fixed. The conditions include: fuel level between 15% & 85% full; engine cold as in first run of the day; outside air temp over 39 degrees F; car driven below 75 mph while going up to normal engine operating temp; barometric pressure more than 75 kPa (so apparently the test won't run in high mountains or during a hurricane!)

    Good luck - these evap system faults are sometimes hard to track down.

  16. #15
    Otten33 is offline Cadillac Owners Member
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    Re: PCM code P 0446

    Thanks 70cougar. I think it is caused by the fuel pump since it started after they replaced the fuel pump. Checking the FTP is probably a good start.

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