Check Engine Light

• Loose Gas Cap: Your gas cap is loose, broken, or simply missing. Gas cap issues can reduce fuel pressure and allow fuel vapors to escape, reducing fuel economy and increasing harmful emissions.
• Failing Catalytic Converter: Your catalytic converter can eventually clog with material, especially with higher mileage vehicles. The catalytic converter is a vital part of the emissions system, removing toxic carbon monoxide. A failing or clogged catalytic converter can severely impact fuel economy and vehicle performance.
• Dirty or Corroded Spark Plugs or Spark Plug Wires: Over time you will eventually need new spark plugs or spark plug wires. Your spark plugs create a hot spark that ignites the air-and-fuel mixture in the cylinder, allowing your engine to start and run. Faulty spark plugs or spark plug wires can cause your engine to misfire, reducing fuel economy, performance, and even prevent it from running altogether.
• Faulty Oxygen Sensor: Due to long exposure to hot exhaust gas, your oxygen sensor might need replacing. The oxygen sensor provides vital air-fuel mixture information to the ECU. A faulty oxygen sensor can cause your vehicle's computer to supply the engine with too much or too little fuel. An engine with too little fuel is at risk of total engine failure, and an engine with too much fuel will create excessive smoke and odor.
• Faulty Mass Air Flow Sensor: When exposed to dirty or particle-rich air, the Mass Air Flow (MAF) sensor could fail. Like the oxygen sensors, the MAF sensor measures the amount of air entering the engine and help ensure the proper air-fuel mixture. A faulty MAF sensor can cause your engine to misfire, ultimately causing poor fuel economy, performance, and potentially more unnecessary damage to your engine.

OBD-II Trouble Codes

When your vehicle has a problem and your check engine light comes on, the On-Board Diagnostics (OBD) system in your vehicle will also trigger a code that can be used to diagnose what might be wrong. If you have access to an OBD-II scanner, feel free to search our database of common OBD-II trouble codes to help figure out what might be wrong.

The way your check engine light is behaving though can help you determine what might be wrong with your Chevrolet, and the severity of the issue. To help you better understand what you should do next, we've outlined possible scenarios:

• The check engine light only comes on in certain conditions: If the check engine light is coming on intermittently, be sure to notice any changes in the performance of your vehicle when the light is on. If you do notice a difference, try driving your vehicle as little as possible until you can bring it in for service. Most likely something is on the verge of failing and you run this risk of your vehicle not starting again.
• The check engine light is constantly on: Your vehicle's onboard diagnostic system has determined something is wrong and needs to be fixed. Although your vehicle may seem to be operating fine, it's best to bring it in for service as soon as possible to prevent additional issues.
• The check engine light is on and there is a noticeable performance issue: If you are noticing a consistent decrease in performance with the check engine light on, your vehicle may have automatically entered a "limp-mode" to prevent additional damage. In this case, you should come straight to our service center or have the vehicle towed to prevent any damage to the engine..
• The check engine light is blinking while driving: Not to be confused with the light occasionally flickering in the first situation, if your check engine light is blinking consistently that typically indicates there is a major issue with your vehicle and you should pull over when safe. If you are not close to our service center, we suggest having your vehicle towed here just to be safe.

How Do I Reset My Chevrolet Check Engine Light?

It's never a good idea to ignore a Check Engine Light, but if you've identified the problem to be a minor issue such as a loose gas cap, the light may go off once the cap is tightened. After a few driving trips, the light should turn off if no potential emission control system malfunction exists. Similarly, other faults once corrected will cause the light to turn off after driving for a short distance. Several Chevrolet vehicles will require a diagnostic scan tool to reset the light if the problem is more severe. We recommend having an authorized Chevrolet technician perform this procedure.