Check Engine Light
An orange indicator light labelled CHECK ENGINE or SERVICE ENGINE SOON, it's also known as the MIL (Malfunction Indicator Lamp) in technical jargon. The importance and function of this light became more critical starting in 1996, when the second generation of onboard diagnostics, known as OBDII, became standard equipment on all makes and models of cars.
Required by for tighter emissions control, OBDII has the ability to monitor a diverse range of engine-related functions and record critical information. You can think of this information as your car's electronic "vital signs." OBDII information has proven to be so credible that it is now being used by some jurisdictions in the United States and around the world as part of their emissions testing programs. The SERVICE ENGINE SOON or CHECK ENGINE LIGHT has several modes and can indicate a normally functioning system, a system that requires prompt attention, and a system that needs immediate attention.
If your car's OBDII system is functioning properly, the CHECK ENGINE or SERVICE ENGINE SOON light should flash briefly when you turn your car's ignition key to the on position. After the brief flash, the light should go out and remain off while you are driving.
A glowing CHECK ENGINE or SERVICE ENGINE SOON light alerts you to problems in your car's onboard diagnostic system that should be checked out as soon as possible. There's no reason to panic and in many cases, you won't notice any difference in vehicle performance.
First, check the gas cap to make sure it wasn't left loose after refuelling. Sometimes, this can trigger the light. Most OBDII-equipped vehicles have a gas cap that simply snaps in place, when turned to the right. Some early OBDII-equipped vehicles have threaded caps. On these, just turn the cap to the right until it begins to click. If the gas cap was loose, the light should go out after a few short trips.
If the gas cap wasn't the problem and the light remains on steady, have the system checked out as soon as possible. A light that flashes requires more prompt attention, indicating a more severe condition that must be checked out immediately to prevent damage to the catalytic converter. When you experience a flashing light, minimize driving at high speeds or under heavy loads. When scheduling service, make sure the shop that diagnoses your car has technicians who are properly trained and certified for OBDII diagnosis and repair.