XG300 goes into limp mode for no apparent reason

Discussion in 'Hyundai Grandeur / Azera / XG' started by B Crawford, Oct 29, 2007.

  1. B Crawford

    B Crawford Guest

    I have had my 2001 XG300 do this twice now some 10 months & 15,000 km apart.
    For no apparent reason the car will suddenly show a 'check engine' light &
    at the same time go into 'limp mode'.
    The car has only 115,000 Km (about 70,000 mi), has been serviced regularly
    & was/is running absolutely perfectly. On both occasions, I was driving
    highway speeds in a remote part of Wa state doing the speed limit & slightly
    accelerating. On the first event I was over an hour from anywhere with a
    code reader, so tried a momentary disconnect of the battery. The problem was
    immediately fixed. It ran perfectly for all these 10 months- I even carried
    my code reader with me for about 9 months in case it should happen again,
    but recently in getting the car ready for winter brought it in the house. So
    once again I had to disconnect the battery roadside (not fun at 6:300 AM on
    a cold desolate road).
    On both occasions there were no codes showing when I got home some 4 hours
    of driving later. Until last week, I dismissed the first as a fluke, but
    here it's happened again & I have no idea what to look for. By the way last
    spring I changed the plugs & checked virtually all electrical connectors
    that I could find under the hood. Everything looked good. The car starts
    quickly, runs smoothly, has all kinds of power & seems almost perfect. The
    almost is b/c at times the remote control for locking doesn't flash the
    lights even though it locks & once in a long while the alarm will sound even
    when opening a door locked & then unlocked with the remote. I mention this
    b/c when the car acted up last week, it also tripped the alarm after I had
    reset the computer, drove it for an hour,then stopped and opened the
    door -causing the alarm to sound.
    Any ideas folks??
    Thanks,
    BCinBC
     
    B Crawford, Oct 29, 2007
    #1
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  2. B Crawford

    hyundaitech Guest

    It's pretty much guaranteed your remote issue is unrelated to the limp-home
    issue.

    It's also going to be impossible to determine the nature of the problem
    causing activation of limp-home without a trouble code. Considering the
    problem has only happened twice in ten months now, the chances of finding
    it without retrieving a code (and taking a guess based off that code) are
    near zero.

    When you use the term "limp-home," do you mean that the transmission
    shifts to and stays in third gear, or that engine power is reduced to near
    zero.
     
    hyundaitech, Oct 29, 2007
    #2
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  3. B Crawford

    B Crawford Guest

    Thanks for responding hyundaitech,
    I don't know what gear it drops to, but last week it cut out as the
    service light came on just as I was ascending a mid grade hill. I had maybe
    500' to go to get past the guard rail & onto a wider shoulder. The engine
    was running very rough & it was a chore to make it at about 5 to 10 mph.
    When I put it neutral , I thought it would stall & trying to rev it didn't
    really make much of a change -speeded up a bit but just as rough. As I said
    a quick battery disconnect for 30 seconds & then it fired right up & has run
    perfectly again for a good 800 km. of mostly mountain driving. I guess I'm
    just going to have to be sure to carry my code reader. The other odd thing
    is that the door locks are now working correctly -every time I lock the
    lights flash twice. For the previous month frequently the doors would lock
    from the remote but no flash & sometimes I'd hear a click but they didn't
    lock. Weird, I realize & yes most likely a red herring but then again the
    whole event is bizarre.
    BCinBC
     
    B Crawford, Oct 30, 2007
    #3
  4. B Crawford

    hyundaitech Guest

    Since the engine performance is limited, it's definitely and engine control
    related issue. Typically, it's either with the accelerator position
    sensor, or some issue with the throttle body or one of its components.

    Next time, try turning the car off and restarting. It may not be
    necessary to disconnect the battery, but rather just start a new key
    cycle.
     
    hyundaitech, Oct 30, 2007
    #4
  5. B Crawford

    B Crawford Guest

    Thanks again Hyundaitech,
     
    B Crawford, Oct 31, 2007
    #5
  6. B Crawford

    Dwight Jones Guest

    I had a similar problem a few years ago with an XG300. They replaced the
    throttle body and it worked for a while, but went out again and the problem
    turned out to be a wiring issue and not the throttle body. Hyundai
    reimbursed me for the throttle body cost and once the frayed wires were
    repaired it ran ok.

    Might want to check the wiring before major repairs.
     
    Dwight Jones, Oct 31, 2007
    #6
  7. B Crawford

    B Crawford Guest

    Thanks Dwight,
    The wiring on these cars is extremely involved. Do you have any idea as to
    where the wiring problem was located?
    Thanks,
    BCinBC
     
    B Crawford, Nov 1, 2007
    #7
  8. B Crawford

    Dwight Jones Guest

    don't recall, sorry
     
    Dwight Jones, Nov 2, 2007
    #8
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