In this guide, we will be going over common problems that can trigger Chevrolet check engine light(s) to appear and how to diagnose the issue(s) yourself.
What does Chevy Check Engine Light Mean?
When your Chevrolet check engine light stays on, it means that the On-Board Diagnostic (OBD) system has detected a problem with the engine, emission system, or transmission. A fault code is stored in the Engine Control Unit (ECU).
Chevy check engine light should only be on for a few seconds when you turn on the ignition and should turn off once the engine fully starts. If your Chevy check engine light stays on or is flashing, get the vehicle diagnosed as possible.
Chevrolet check engine lights may also be referred to as Malfunction Indicator Lamps.
Common symptoms include:
- Engine shaking
- Poor throttle response
- A decrease in fuel economy
- Engine misfire
- Difficulty accelerating
- Car won't stay running
- Check engine light flashing
Chevy check engine lights may stay on, but with no performance symptoms. Even if there are no symptoms, it is important to read the fault codes to find out why there is a CEL on.
Common problems that can trigger Chevy check engine lights to stay on include:
- Loose gas cap / damaged seal
- Faulty Mass Air Flow (MAF) sensor
- Spark Plugs
- Faulty ignition coil
- Bad oxygen (O2) sensor
- Dirty fuel injector
- Bad fuel filter or pump
- Catalytic converter
- EVAP leak
First, check the gas cap and make sure it is on tight. If the light doesn't reset within the next two to three days, proceed to read the fault codes.
How to Diagnose Chevrolet Check Engine Light
Follow the instructions below to read Chevrolet service engine light codes. For this procedure, you will need an OBD-II scanner.
- Locate the diagnostic port under the dashboard of your Chevrolet on the driver's side. This is a 16-pin port on all 1996 and newer Chevrolet vehicles have this port. Plug in your OBD2 scanner or Bluetooth adapter into the port.
- Turn the ignition ON, key in position II. All Chevrolet dashboard lights will turn on but do not start the engine. If your Chevrolet has Start/Stop button you will need to press the START button without pressing the brakes.
- Allow your OBD2 scanner to turn on and connect to your Chevrolet Engine Control Unit (ECU). This step can take up to one minute.
- Read Chevrolet check engine light codes from the Engine Control Unit (ECU) using an OBD-II scanner.
- Once you have retrieved the codes, write them down. Research the codes and fix the underlying problem, you can come back to reset the Chevrolet check engine light.
The fault codes are just the starting point. Research every present code and common problem. Don't replace parts based on the fault code only. Get the opinion of a professional mechanic before replacing any parts.