98 Deville Concours Check Engine Light
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1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, 98 Deville Concours Check Engine Light in Past Cadillac Vehicle Discussion; Hi folks. My 98 Deville Concours has 52K miles on it and I am second owner. I was told and ...
  1. #1
    faustd is offline Cadillac Owners Member
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    98 Deville Concours Check Engine Light

    Hi folks. My 98 Deville Concours has 52K miles on it and I am second owner. I was told and believe the car was services routinely by a Cadillac dealer before I bought it 3 weeks ago. Today (outside air temp about 40 degrees) while driving sedately at about 60mph, the check engine light came on steady, and then began flashing. There were no other apparent symptoms at first. I stopped and got gas, and when finished filling up I made sure the gas cap was tight. Got in and drove it another 10-12 minutes (maybe 7 miles) at 55-60 mph to get it home. Once I got it home and stopped in the garage, with the car in drive and holding the brake, it seem to be missing (you could feel a slight surge and uneven idle) and there was a gassy fuelly smell. In park with engine idling, I went around back and there was a lot of steam chuffing out of both tailpipes (not just regular 40 degree day fog but what appeared to be s-t-e-a-m...steady chuffing from both pipes.) What is the diagnosis? I am not sure how to read the codes on this car, but what does it sound like is wrong? Dave

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  3. #2
    faustd is offline Cadillac Owners Member
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    Re: 98 Deville Concours Check Engine Light

    Hi folks...me again, 98 concours. I went and read the troubleshooting diagnostic manual that I have on hand (A Chiltons...not good I know but all I have at present) and it said that the symptoms I've described above in my original post probably indicate coolant entering a combustion chamber. The odor I described as gassy or fuel-like is really probably that sweet smell coolant gives off. So, if this is really what is going on, how do I proceed from here? If it is coolant entering combustion chambers, what has most likely happened? Head gasket failure? What else could cause it? What does repair of this problem entail? Have I destroyed the motor? Dave

  4. #3
    cadillactech is offline BAD EMAIL ADDRESS
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    Re: 98 Deville Concours Check Engine Light

    Sound like just a good old fashioned engine miss. The head gasket issue putting coolant in the cylinders is usually more prevalent as a cold start miss. I would suspect a typical secondary ignition problem ( plugs, wires, carbon tracking )

  5. #4
    faustd is offline Cadillac Owners Member
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    Re: 98 Deville Concours Check Engine Light

    Thanks Cadillactech...I did let it cool completely this afternoon, and I just went out and started it again and let it idle a few minutes. It has a steady miss and the check engine soon light is on but when I got right down at the tailpipe, I could not smell antifreeze. I smelled only unburned fuel as near as I could tell. This may be a ray of hope that it ISN'T a head gasket, no? I didn't let it warm fully just now, so it might only start smelling of antifreeze after the cooling system is fully warmed and pressurized, I don't know. But at least I didn't smell coolant just now. Where is BBOB when you need him? Dave

  6. #5
    faustd is offline Cadillac Owners Member
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    Re: 98 Deville Concours Check Engine Light

    Hey guys...me again. I just went again and started the engine...again steady miss and check engine light on steady. I let it idle with the coolant cap off for about 5 minutes...there has been no apparent loss of coolant since I serviced it 3 weeks ago, the level was right where I filled it to back then, and after idling a few minutes tonight there was no bubbling in the coolant tank. Again, I am praying these are signs that the problem is NOT a head gasket. Again, the exhaust smells like unburned fuel, but I cannot smell coolant (and I have tried to make sure what I'm smelling). Thanks for your assistance in advance. Dave

  7. #6
    MetaPhaze is offline Cadillac Owners Member
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    Re: 98 Deville Concours Check Engine Light

    Quote Originally Posted by faustd
    Hey guys...me again. I just went again and started the engine...again steady miss and check engine light on steady. I let it idle with the coolant cap off for about 5 minutes...there has been no apparent loss of coolant since I serviced it 3 weeks ago, the level was right where I filled it to back then, and after idling a few minutes tonight there was no bubbling in the coolant tank. Again, I am praying these are signs that the problem is NOT a head gasket. Again, the exhaust smells like unburned fuel, but I cannot smell coolant (and I have tried to make sure what I'm smelling). Thanks for your assistance in advance. Dave
    These guys showed me someting pretty cool. Turn the key to accessory mode, and press and hold "OFF" and "WARMER". This will turn the OBD system on. You should be able to get the engine trouble code from there. Once you do post it in this thread and I will see if I can find the code for you.

  8. #7
    97 concours is offline Cadillac Owners Member
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    Re: 98 Deville Concours Check Engine Light

    #1 Is your oil milky white on the dip stick ?

    #2 Does the coolent reservoir have signs that combsution is entering it ?
    If the answer is no to both, you more than likely just have a sensor malfuntion or an ignition related problem.

    Once you enter into the diagnostic codes by following the instructions already given, you will more than likely see one or more PCM codes. Let us know what they are. The Northstar uses two sensors located on the engine facing the front of the car just under the exhaust manifold on that side. These sensors are the ignition triggers, and are known to fail. If this is the case you can clear the codes and temporarily clear the problem since one of the two sensors is a backup, but eventually it will set the same code causing the engine to misfire or stall.

  9. #8
    faustd is offline Cadillac Owners Member
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    Re: 98 Deville Concours Check Engine Light

    Hey guys. Thanks for trying to help, but there is NO "warmer" button on a 98 concours. This car has a temp-adjust rotary button you turn to display your desired temperature on the digital display. Everything I read last night told me that there wasn't any way to pull codes on this car without a scan tool, and I don't have one. Maybe someone out there can set me straight and tell me how I might get the codes on a 98 concours. Unless they can, I'm just going to have to take it to a shop. dave

  10. #9
    faustd is offline Cadillac Owners Member
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    Re: 98 Deville Concours Check Engine Light

    Hi. I DID go out just now and check the dipstick and under the oil filler cap for emulsified oil and coolant. Also looked as far as possible up under the valve cover. There is no sign of any water in the oil at all that I can see. dave

  11. #10
    donlampkin's Avatar
    donlampkin is offline Cadillac Owners Member
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    Re: 98 Deville Concours Check Engine Light

    press the passinger temp up button

  12. #11
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    CadillacLuke24 is offline Cadillac Owners Connoisseur
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    Re: 98 Deville Concours Check Engine Light

    Nice! Brought a 7 year old thread back to life!!

    For future reference for anybody doing HG failure research, judging from his symptoms it does sound like his headgaskets failed. Steam rolling out the pipes is a strong indicator that something is amiss with the HGs. A block test (Google it if you don't know ) will confirm it, but like I said the steam is a huge red flag. He also mentioned the coolant smell in the exhaust, which is a dead giveaway that his HGs were toast. For those who don't know, coolant has a sweet smell, and a fishy component. One I've heard that I think hits the nail on the head is "Maple syrup and fish".

    Not sure what caused his SES light to trip, but another sign your HGs are bad is that the vehicle will run rough. Hard starts and rough running in general.

    Hope this helps.

  13. #12
    Lunchbox7688's Avatar
    Lunchbox7688 is offline Cadillac Owners Member
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    Re: 98 Deville Concours Check Engine Light

    damn

  14. #13
    Submariner409's Avatar
    Submariner409 is offline If it won't run, chrome it
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    Re: 98 Deville Concours Check Engine Light

    You're asking a question of someone who has not been here since January of 2005 ! Look at the dates of the first 9 posts.............

  15. #14
    CadillacLuke24's Avatar
    CadillacLuke24 is offline Cadillac Owners Connoisseur
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    Re: 98 Deville Concours Check Engine Light

    Quote Originally Posted by Submariner409 View Post
    You're asking a question of someone who has not been here since January of 2005 ! Look at the dates of the first 9 posts.............
    I know I was goin' for a reference style thread.

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