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 isn't easy 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 the 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 a 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 the 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 the Erase Codes menu. Select YES to clear the 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 straightforward. Any Cadillac owner can read and clear the 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 effortless and takes less than five minutes.


By  YOUCANIC Automotive Experts

Published on: Thursday, April 5, 2018.
Updated on: Monday, January 4, 2021


Vehicle:   Cadillac
Difficulty: ⚫⚫⚪⚪⚪
DIY Cost: $15-$45
Est. Time: 15 min