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  1. #1

    Default Service Engine Soon Light

    Recently I replaced the head gaskets on my 99' GMC Suburban. Since then I have had the SES light on. When I run the codes it comes up misfire. I have replaced everything from the ICM to the plugs. There's a black plug in the middle of the intake with a white safety clip on it and I'm wondering if that isn't the problem. When I replaced the ICM, the coil, and plug wires it wouldn't start. I noticed that the white clip had come lose and reconnected it...and it started. Any ideas??? I just want the #$% light off. :shock:

  2. #2

    Default RE: Service Engine Soon Light

    How many miles have you driven since the gasket replacement? Did it just happen or has the light been on for a while?

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  3. #3


    It came on immediately on the first restart. It started right up and runs fine...just has the light on.

  4. #4
    TrailLeadr's Avatar
    Join Date
    Jun 2005
    Coventry, Rhode Island


    Are the knock sensor, and misfire codes the same?

    Did you re-time the engine, or just mark the distributor, and then replace it at the mark?
    Or is this a DIS system?
    Rhode Island

  5. #5


    It's a DIS system. If I was off a tooth on the distributor would it cause this?

  6. #6
    TrailLeadr's Avatar
    Join Date
    Jun 2005
    Coventry, Rhode Island


    it would throw the timing off, and I'm not sure what degree off it would be at one tooth, but yes, it could cause backfiring, but you'd also have poor performance too.

  7. #7


    Here's a silly question, have you tried driving to see if the engine really does misfire?

  8. #8


    It runs fine, no miss at all. The only difference there is between before/after is the SES light. I was going to try moving the distributor a tooth today, but mother nature had other plans and we're under a blizzard warning. When the weather breaks I'll give it a shot and let you know how it comes out. :D

  9. #9


    Yeah, that's another hazard of doing projects in the winter ... the weather might not cooperate with you. We had flash floods and tornado warnings all day today...

  10. #10


    Pull the bulb

    Sorry but thats just the easy way.

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