1. Oxygen Sensor: A faulty oxygen sensor can affect the air-fuel mixture, causing rough idling and triggering the service engine soon light.
2. Spark Plug or Wire Issues: Worn-out or damaged spark plugs or spark plug wires can cause the engine to misfire, leading to rough idling and the check engine light turning on.
3. Fuel Injector Problems: Malfunctioning fuel injectors or a clogged fuel filter can disrupt the proper flow of fuel to the engine, causing idling problems and illuminating the service engine soon light.
4. Idle Air Control (IAC) Valve: A faulty IAC valve can affect the engine's ability to maintain a steady idle, resulting in rough idling. This can also cause the service engine soon light to activate.
5. Vacuum Leaks: Vacuum leaks can disrupt the proper air-fuel mixture, causing the engine to idle roughly. When the engine control module (ECM) detects these abnormal conditions, it triggers the service engine soon light.
6. Transmission Issues: In some cases, transmission-related problems, such as low transmission fluid or faulty sensors, can affect engine idling and prompt the check engine light to come on.
To accurately identify the root cause and have the issue resolved, it's best to have your 1995 Chevy Blazer diagnosed by a professional mechanic or take it to a reputable automotive repair shop.
