Question about 1999 Buick Century

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99 buick century OBD MIL light is inoperable but comes on when ignition is turned to on position so bulb is not burnt out what could be the cause I have a PO440 code

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The check engine light sounds like it is working as it comes on for a bulb check when you start the car. If there is a code but the check engine light is not on than the code is not active. Another way to explain it is there may have been a problem at one time. The problem might have been intermittent or resolved itself. Once the PCM doesn't see the problem for a while it will turn off the light but keep the code in its memory. I would clear the code and see if it comes back.

Posted on Nov 28, 2012

  • app_3rp93055
    app_3rp93055 Nov 28, 2012

    I have cleared the code but it comes back and the mil still doesn't light up.

  • Jeremy W.
    Jeremy W. Nov 29, 2012

    Are you sure the code is cleared? How long does it take to come back?



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Posted on Jan 02, 2017

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SOURCE: Need to replace tail light bulb on 1996 Buick Century

Inside the trunk, under the carpet behind the tail lights will be a whole bunch of small plastic nuts, running from one side of the car to the other. Take all of these plastic nuts off, and the whole tail light assembly will come off in one large piece. Find the bulb you need to replace, and reassemble

Posted on Apr 06, 2009

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SOURCE: 99 buick century headlights

u changed the multifunction switch or the main head light switch?

Posted on Sep 09, 2009

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Yeah, I think you're right. Bulbs don't burn forever, though yours may have tried-lol. Pull the cluster or wherever it's at and change the bulb. The number or type should be on it. Take your battery off before you start. When you have a new bulb in, start the car and if the light goes off, go immediately for the inspection, before the light has a chance to come back on If the light is on when the car is running, it may not pass then either...kind of a catch 22.

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How to reset warning lights

Welcome to

Oil Change light:

To reset the "CHANGE OIL" light, turn the ignition switch to the run position with the engine off. Fully depress and release the accelerator pedal three times within 5 seconds. The light will flash twice and go out.

Maintenance warning light? MIL? Check engine? Maintenance Required?

You will have to go to Auto Zone to have the code read and then fix the code problem and then clear code with code reader

Regards, Lee Davidian

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Nov 05, 2010 | 2001 Buick Century

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well u have to take out the head light clips which are on the sides of the head light then pull out the head light and uncover the second rubber cover i believe then reach in the head light and turn the socket to the left and and should come out the just change the bulb...when putting the bulb back just turn it to the right and put back the head light and rubber cover and the side clips and thats it...good luck

Jun 22, 2009 | 1988 Buick Century

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What does code 1-p0650 mean?

P0650 Malfunction Indicator Lamp (MIL) Control Circuit Malfunction

Malfunction Indicator Lamp (MIL) is located on the instrument panel. When the ignition switch is turned ON without engine running, MIL will light up. This is a bulb check. When the engine is started, MIL should go off. If MIL remains on, the on board diagnostic system has detected an engine system malfunction.

Possible Causes:
  • Harness or connectors (MIL circuit is open or shorted.)
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    I had the same exact issue.
    I had to buy a new multi-function switch for 200 dollars
    and put it in.

    May 09, 2009 | 1999 Buick LeSabre

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    1992 Buick Century turn signal

    You may have some corrosion in the socket where you plug in the bulb. This would cause the lights to not blink. Put the turn signal on, and check the lights, front and back. Are then on, and not blinking, or are they not on at all? If the bulbs are good, and they aren't on, it's the bulb socket problem. Get fine sandpaper, fold it around a pencil eraser, sand off any gunk or corrosion inside the socket. It could also be a faulty ground wire, check for a loose wire at the light assembly. front and back.countrycurt0

    Aug 22, 2008 | 1992 Buick Century

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