Service Engine Soon Light

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by cornboy, Dec 27, 2006.

  1. cornboy

    cornboy New Member

    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. ChevyFan

    ChevyFan The Sheriff Staff Member 5+ Years 5000 Posts

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

    cornboy New Member

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

    TrailLeadr Epic Member 5+ Years 1000 Posts

    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?
     
  5. cornboy

    cornboy New Member

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

    TrailLeadr Epic Member 5+ Years 1000 Posts

    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. ChevyFan

    ChevyFan The Sheriff Staff Member 5+ Years 5000 Posts

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

    cornboy New Member

    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. ChevyFan

    ChevyFan The Sheriff Staff Member 5+ Years 5000 Posts

    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. 84fiero123

    84fiero123 Epic Member 5+ Years 1000 Posts Platinum Contributor

    Pull the bulb

    Sorry but thats just the easy way.
     

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