The "check engine" light is part of your vehicle's so-called onboard diagnostics (OBD) system. When it finds a problem in the electronic-control system that it can't correct, the computer turns on a yellow warning indicator that's labeled "check engine," "service engine soon" or "check powertrain." Or the light may be nothing more than a picture of an engine, perhaps with the word "Check." In addition to turning on the light, the computer stores a "trouble code" in its memory that identifies the source of the problem. The code can be read with an electronic scan tool or a diagnostic computer, standard equipment in auto repair shops.
When your car is trying to tell you something, don't ignore it. The check engine light can be triggered by a number of issues. It's important to promptly address problems indicated by the light. Ignoring them could lead to larger, more costly problems later.
If the Check Engine light illuminates, it will either blink or remain constant, depending on the problem. If the light is steady. The problem is not an emergency, but you should schedule an appointment as soon as possible. A blinking light usually indicates a severe engine misfire allowing unburned fuel to be dumped into the exhaust system. There it can quickly raise the temperature of the catalytic converter to a point where damage is likely, requiring an expensive repair. If this occurs, you should reduce power and have the vehicle checked as soon as possible.
The most common reasons for a check engine light coming on, and the vehicle repairs associated with it.
- Oxygen sensor (part of the emissions system, monitoring and helping adjust the air-fuel mixture) failure. Faulty sensor can cause damage to spark plugs and catalytic converter.
- Loose or damaged gas cap. The gas cap seals the fuel system and helps maintain pressure within the fuel tank. Usually fixed by getting a new gas cap.
- Failing catalytic converter (helps protect our environment by converting harmful carbon monoxide into carbon dioxide). Damage usually occurs due to neglected maintenance.
- Faulty ignition coils and spark plugs. The ignition coil charges the spark plugs by converting low voltage electricity from the car’s battery into high voltage electricity that can get the plugs going. Both coils and plugs can fail just from the amount of high temperatures they’re exposed to, as well as due to general aging.
- Problem with the mass airflow sensor (monitoring the amount of air mixed in the fuel injection system). Faulty sensors can cause damage to spark plugs, O2 sensors or catalytic converter.
- Bad spark plug wires. Worn plugs and plug wires can cause clogged catalytic converter or damage to ignition coils and O2 sensors.
- Bad vacuum hose (helping to prevent pollution). Sometimes the vacuum hoses in the system are damaged and cause the system to fail. This is relatively easy to fix, only requiring new hoses most times.
- Exhaust gas recirculation (EGR) valve problem. EGR is a system that cuts down the amount of nitrogen oxide that comes out of your car and helps it run more efficiently.The failure of this system can cause your car to idle roughly or misfire, because the engine is not circulating the extremely hot air properly.