Question about 1987 Cadillac DeVille

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What is the problem when my check engine soon light comes on. is it mechanical or emissions 1987 cadillac deville

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  • Scott Heller Mar 05, 2009

    thank you very much

  • Scott Heller Mar 05, 2009

    a guy put a gauge on my car today 1997 cadillac and he said i had a vaacum leak causing the service engine soon light to come on. how do you find out the most economical way to find this leak. my monies are tight since i just got laid off thanks scott



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You can't tell what the problem is just by the presence of the "check engine light." Many sensors can set off the light. You can connect a diagnostic analyzer to the vehicle and it will spit out codes that you can look up to see what the problem is. That is what most shops do, or you can buy an analyzer and do it yourself. It may be harder to find one for a 1987 car though

Posted on Mar 05, 2009


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Check engine light flashing check engine soon smell of gas and not running smouth

Check engine light flashing means there is a bad misfire , it flashes to tell you your damaging your catalytic converter . You need to have it check , you don't won't to have to replace the catalytic converter . Can cost up to $1,000.00 . Flashing Check Engine Light CarMD

Feb 03, 2016 | 2004 Cadillac Deville

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P0440 indicates the failure of the EVAP system to develop proper vacuum. If you got
and replaced a proper good quality gas cap, you have corrected the most common cause.
However, in fully searching the causes of this code ( ) (pardon the generic GM info, but will apply for you)-----you will find there are 5 other causes of the vacuum failure, which are independent of the gas cap. Your good local mechanic can sort those out; I would save your gas cap
receipt if you were advised to buy one not needed. As you probably know, your
State emission test facility checks your gas cap----so that is another way to find that specific portion of this answer,
(for their fee).
P0300 is a generic misfire code. For this, a specific Cadillac forum may be most
helpful = 2001 Deville intermittent service engine soon light code P0300
co-logo-100x100.png 2001 Deville intermittent service engine soon light code... I recently bought this car from an owner who took decent care of it but a week after i bought it, the service engine light appeared. After a few View on www.cadillacforums... Preview by Yahoo You will see that this generic code is perhaps more serious, costly, and harder
to track down than the P0440. You will also discover that P0301 is cylinder 1 misfire, P0302 is cylinder 2, and etc, etc. If you get a good diagnostic, they will generally
be able to localize the problem fairly specifically---and get a more specific fix. The person who reported this code was unhappy because he was given several ($$) fixes,
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Jun 04, 2014 | 2001 Cadillac DeVille

1 Answer

Service engine soon light on

Go to a shop that can check your computer box and it will show what is causing the light to come on. Be careful, make sure you trust the mechanic.



Oct 25, 2013 | 2005 Cadillac Deville

1 Answer

How to reset the Service Engine Soon warning lamp on a 2003 Cadillac DeVille?

"Service Engine Soon" message means that the PCM (Powetrain Control Module aka engine computer) has detected a fault in the fuel, ignition, or emission systems. It is the same as a Check Engine light.

This could be something as simple as a loose fuel cap, or it could be a circuit problem with a component like a fuel injector, O2 sensor, temp sensor, emission system component, etc. When this message appears the PCM stores a trouble code that tells the technician what component is acting up.

This code can be read with a scan tool or code reader. Once the code is retrieved, then the tech can follow the diagnostic procedure for that code and troubleshoot it and then repair it. Most shops (and the dealer) have the equipment to do this. Autozone and some auto parts stores also have a scan tool that will connect to your Cadillac and read the code so you would have an idea as to what component is setting the code; most auto parts stores will check this for no charge.

If the vehicle seems to run ok, then I would not worry too much, but still get the code checked as soon as it is convenient. If the vehicle is running bad, then get this checked as soon as you can because continued driving it may cause further damage.

Hope this helps and just keep in mind that your feedback is important and I'll appreciate your time and consideration if you leave some testimonial comment about this answer. Thank you for using FixYa.


Oct 20, 2011 | 2003 Cadillac Deville

1 Answer

My 1987 cadillac deville service soon light has come on a few times in the last week, doesn,t stay on...and now today my service now light (which is located right above the service soon light) came on for...

Not sure if you got an answer, however first thing you should have done was take it to AutoZone or someone with "diagnostic" computer module they can hook it up and tell you quickly. I know that my "soon" did the same thing and then "NOW" thinking it would go away like the fore mentioned "soon" and my TIMING chain busted. One thing you aren't told about when maintaining a fancy elite Cadillac or any other luxury car. The "maintenance" changes drastically. I had no idea that the timing chain needed adjusting every 60,000 miles. I had purchased my Cadi third hand and 105,000 miles. So at 140,000 miles it was way past due. Unfortunately, to replace the chain they had to remove the front of the engine. A $60 part cost $1300 to fix, but I did and she still IS the cat's meow.Point being, even though it was the early stages of computers/there is a diagnostic panel under the ashtray that can be used to trace these unforeseen problems.Hope your Cadillac is still going strong.

Jul 15, 2011 | 1987 Cadillac DeVille

1 Answer

01 deville running rich. Why?

emission issues. check all vacume lines for cracks. 01..its time for new ones. check all electrical conections e

Feb 19, 2010 | 2001 Cadillac DeVille

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Service engine soon light come on and off than emission pop up

you need 2 replace your oxygen censor and check your evap for any leaks

Jan 20, 2010 | 1996 Cadillac DeVille

1 Answer

My service engine soon light ccame on, but car runs great

U will very seldom feel any difference when this light comes on, it comes on when one or more of about 200 electronic faults has occured in the electronic controls and sensors of the computer controled systems, these systems are the engine the transmission and the emission control system, you will need to have the system tested to see what code or codes is stored in the computers memory.

Jul 17, 2009 | 1996 Cadillac DeVille

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