Cadillac Check Engine Light Stays On

Is your Cadillac Check Engine Light ON or Flashing? In this guide, you will learn about common problems that trigger Cadillac check engine light to come on.

You will also find step-by-step instructions on how to diagnose the Cadillac check engine light yourself.


cadillac check engine light on

Symptoms of a check engine light can vary depending on the fault code that triggered the light. Possible symptoms include:

  • Poor throttle response
  • A decrease in fuel economy
  • Engine misfire
  • Difficult to accelerate or going uphill
  • Engine shakes or excessive vibrations
  • Car won't stay running

The check engine light may be on, with no symptoms. Even if there are no symptoms it is important to read the fault codes to find out why CEL is on.

Common Causes

Cadillac check engine light can turn on for various reasons including something as simple as a loose gas cap.

  • Loose gas cap
  • Faulty MAF sensor
  • Oxygen sensor
  • Catalytic converter
  • EVAP leak
  • Vacuum leak
  • EGR Valve

It is difficult to know the cause of the check engine light without reading the codes.

How to read Cadillac codes

The following steps provide information on how to read Cadillac fault codes from the Engine Control Unit (ECU).

What you will need

You can purchase a scanner online or borrow one from your local auto parts store.


  1. Locate OBD-2 port under the dashboard of your Cadillac on the driver's side. This is a 16-pin port and all 1996 and newer Cadillac vehicles have this port.

  2. Connect Scanner. Plugin your scanner or Bluetooth adapter into the OBD2 port. Cadillac Check Engine Light ON Troulbeshooting

  3. Turn ignition ON, key in position II. All Cadillac dashboard lights will turn on but do not start the engine. If your Cadillac has Start/Stop button you will need to press the START button without pressing the brakes. How to diagnose Cadillac check engine light service engine soon ATS, CTS, XTS, CT6, XT5, Escalade, SRX, DTS, STS, BLS, XLR

  4. Turn on scanner. Allow your OBD2 scanner to turn on and connect to your Cadillac Engine Control Unit (ECU). This step can take up to one minute. Check Engine Light On Cadillac

  5. Read Codes. Read Cadillac check engine light codes from the Engine Control Unit (ECU) 

  6. Clear Codes. Once you have read the codes and fixed the underlying problem, you can come back to clear Cadillac CEL codes. Go to Erase Codes menu. Select YES to clear Cadillac check engine light. clear Check Engine Light On Cadillac

  7. Check engine light codes should only be cleared (erased) only after the problem that triggered the light has been fixed.
Reading Cadillac check engine light codes and resetting it once you fix the problem is very easy. Any Cadillac owner can read and clear Cadillac check engine light at home.
This procedure works on Cadillac ATS, CTS, XTS, CT6, XT5, Escalade, SRX, DTS, STS, BLS, XLR and other models.

OnStar Subscribers

diagnose cadillac check engine light via onstart

If you are subscribed to OnStar, press the button to connect to an Advisor. They can run a diagnostic check and retrieve the trouble code(s) from the Engine Control Unit (ECU).

If you are not subscribed to OnStar follow the instructions to read the fault codes yourself. This procedure is very easy and takes less than five minutes.



My car has less then 96k miles and the check engine light came on and it showed codes p0017 & p0008. Gm issues a service bullentin (11340) and later extended it to include the 2009 Cts ( 11340c) for premature timing chain wear. Even though my cars make, model and year is listed under sb 11340c, when you call gm, they say my VIN isn't included. Obviously, my car which year is listed should be covered and gm should repair under this sb. It is the exact same issue the sb was issued for. Gm is scamming their customers and there needs to be a recall for this issue. I read thousands of people complaining about the same issue, and all that needs to happen is for the htsa to require all the 2009 Cts that had to have this issues repaired at their own expense while gm reaps the rewards of each car that they have a known engineering issue.

  • Log in or register to post comments
  • Visitor

    2015 Cadillac SRX. I changed my low beam head light bulbs to LED bulbs trying to get more light. Now the check engine light is on. Is this related?

  • Log in or register to post comments
  • Visitor

    I have a 2007 escalade and I have few warning lights on. The scanner pointed me to a couple of the problems but on a couple others it said it cant connect to the ecu. Why is it reading some problems and not others?

  • Log in or register to post comments
  • Visitor

    Can a past due on you're oil change or due on the date cause check engine light to come on a ats 2014

  • Log in or register to post comments
  • Visitor

    No the check engine light should not come on because you haven't changed the oil. Hope this helps.

  • Log in or register to post comments
  • Visitor

    My 2005 Cadillac cts chef engine light came on after my car was shut off and stays on and drains my new battery. What could be causing the issue please help. This is one among a few issues I've been having. Really love this car.

  • Log in or register to post comments
  • Visitor

    Hello my name is Jeanette I have a 2007 Cadillac STS my engine light on I went to O'Reilly to get it checked and they gave me codes I do not understand p0455 p0301 p0300

  • Log in or register to post comments