Cadillac Check Engine Light Stays On

This guide provides step-by-step instructions on how to diagnose the Cadillac check engine light yourself.

Symptoms

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
• The 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

• OBD-II scanner

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

Procedure

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.

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2. Connect Scanner. Plugin your scanner or Bluetooth adapter into the OBD2 port. 

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. 

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. 

   

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. 

   
7. Check engine light codes should only be cleared (erased) only after the problem that triggered the light has been fixed.