Engine warning light

9 Reasons Why Your Check Engine Light is On

The Check Engine Light (CEL) in your car illuminates when your car’s main computer senses that something is wrong.  When it illuminates, the repair technicians at East Hills Chevrolet of Roslyn, a top Chevrolet dealer in NY state it is rarely an emergency situation but it is something that you may wish to bring to a mechanic to evaluate as soon as you can.  In case this every happens to you, or if it has happened, here are the “top nine” reasons that a CEL light goes on.

The Evaporative Emissions (EVAP) Purge Solenoid needs replacing

The purge solenoid is part of your car’s EVAP system and helps control how much fuel vapor escapes into the atmosphere. The solenoid is controlled by the main CPU module and could be partially left open.

The Evaporative Emissions (EVAP) Purge Control Valve needs replacing

The Purge Control Valve is another part of the car’s EVAP system.  When your car’s engine is fully warmed up, the main CPU module gradually opens the purge valve to allow some of the fuel vapor to be sucked from the charcoal canister to be burned in the engine.

Spark Plug Wire(s) and Spark Plug(s) issues

Faulty spark plug wires and/or spark plugs can cause a “misfire,” reducing gas mileage and potentially damaging the car’s catalytic converter.  If this is the issue that is happening to your car, then you likely need to replace the spark plugs and wires.

Mass Air Flow Sensor needs replacing

The mass air flow sensor measures the air coming into your car’s engine and works with the main CPU to determine how much fuel to inject into the engine. When the mass air flow sensor is malfunctioning, fuel economy will usually drop and the engine will run rough.

Ignition Coil(s) need replacing

Ignition coils provide high voltage to the spark plugs. Like spark plug wires, several conditions can result in the failure of ignition coils, including high engine bay temperatures and age. Vehicle owners should pay special attention since ignition coil failure damage the car’s catalytic converter.

Thermostat needs replacing

The thermostat is responsible for regulating the engine coolant temperature in the engine block/radiator system. When a thermostat fails, if often gets stuck open. If the vehicle’s computer doesn’t see the engine coolant temperature rise to operating temperature within a certain period of time, it will illuminate the check engine light. The solution is to replace the thermostat.

Tighten the Fuel Cap

Believe it or not, your fuel cap needs to be tightened in order for your car’s EVAP system to function properly. If your CEL light ever comes on, the first thing to do is check that your fuel cap is on tightly.

Catalytic Converter needs replacing

Hopefully you never need to replace your catalytic converter because they are quite expensive.  In most cases, a catalytic converter won’t fail unless a misfire occurs, which can be caused by ignoring a faulty spark plug, ignition coil or engine mechanical problem.  Bottom line: if your CEL illuminates, have a mechanic look at it.

Oxygen Sensor needs replacing

The most common car repair when the CEL illuminates is a bad oxygen sensor. The O2 sensor is extremely important to a car’s engine performance.  O2 sensors can fail prematurely for a variety of reasons but usually it’s just a matter of age.  If ignored, a faulty O2 sensor could result in as much as a 40-percent reduction in gas mileage.