1. Faulty Oxygen Sensor: The oxygen sensor plays a crucial role in monitoring the oxygen content in the exhaust gas and helps regulate the fuel-air mixture. A malfunctioning sensor can trigger the Check Engine Light.
2. Catalytic Converter Issues: The catalytic converter helps clean and purify harmful emissions before they are released from the vehicle's exhaust system. A clogged or damaged catalytic converter can trigger the Engine Light.
3. Spark Plug/Ignition Coil Problems: Worn-out spark plugs or faulty ignition coils can disrupt smooth combustion, causing misfires. These issues can activate the Check Engine Light.
4. Faulty Mass Air Flow (MAF) Sensor: The MAF sensor measures the amount of air flowing into the engine. Incorrect readings from a faulty MAF sensor can cause performance problems and trigger the Engine Light.
5. Evaporative Emission System Problems: The evaporative emission system controls and prevents fuel vapors from escaping into the atmosphere. A leak or malfunction in this system can turn on the Check Engine Light.
6. Engine Misfires: Engine misfires occur when one or more cylinders fail to combust properly. This can be due to various reasons such as faulty fuel injectors, worn-out spark plugs, or compression problems. Engine misfires can trigger the Check Engine Light.
7. Loose or Damaged Gas Cap: A loose or damaged gas cap can cause pressure loss in the fuel system. This can lead to incorrect readings from the vehicle's sensors, potentially causing the Engine Light to illuminate.
8. Transmission Issues: In some cases, the Check Engine Light may come on due to transmission-related problems, such as a faulty transmission control module or low transmission fluid levels.
9. Faulty Knock Sensor: The knock sensor detects any unusual knocking or detonation noises inside the engine. If it malfunctions, it can disrupt the engine's timing, leading to the Engine Light coming on.
10. Exhaust Leaks: Leaking exhaust components, such as pipes or connections, can affect engine performance and emissions, potentially triggering the Check Engine Light.
11. Computer Software/Sensor Problems: Sometimes, software glitches or faulty sensors can provide incorrect data to the vehicle's computer, resulting in the activation of the Check Engine Light.
12. PCM/ECM Issues: Problems with the Powertrain Control Module (PCM) or Engine Control Module (ECM), which are responsible for managing various engine functions, can also cause the Engine Light to illuminate.
Note: It's important to have the specific diagnostic trouble code (DTC) read from your Envoy's onboard diagnostics system to identify the exact cause for the Check Engine Light being on. This can be done using a scan tool or by taking the vehicle to a qualified mechanic or service center.
