Modern vehicles have an inboard computer analytical system that continually monitors the key operating systems, especially your engine and transmission system. The key reason for checking these systems is to make sure that the car is operating at maximum efficiency with the least possible emissions. Given that emission control and fuel economy have become more important, your car’s electronic system needs to continually adjust and tweak several parameters based on the existing driving conditions, including vehicle load, air or fuel mix and temperature to name just a few. When any of these parameters fall outside the tolerable range for operating a car, your check engine light will come on to notify you of an existing problem. As the vehicle owner, you should take your vehicle to a certified auto mechanic to restore it back to manufacturer specifications.

Possible reasons behind the check engine light

Issues with the mass air flow sensor

Initially, you may not encounter any severe driveability issues, though you may notice sluggishness or a reduction in power in your car’s system. This may be traced back to the mass air flow sensor which may be defective.

Lean condition

Modern vehicles use oxygen sensors to detect whether the air/fuel combination is too lean or too rich. If excess oxygen is detected, the computer assumes the mixture is very lean which means there’s not adequate fuel. Some of the lean symptoms include poor power output and the engine system running hotter than usual among other symptoms.

Rich condition

Likewise, if small amounts of oxygen are detected, the computer assumes the air/fuel combination is too rich, meaning either excess fuel or little oxygen. Symptoms include poor fuel mileage, excess fuel thinning, which quickly causes fresh engine oil to turn black, and build-up of sooty carbon residues on spark plugs. This condition is as a result of a defective or dirty mass air flow sensor.

Cylinder backfire

You may experience difficulty starting your engine, or the engine might idle, stumble or dillydally among a host of other driveability problems. This could be traced back to a defective spark plugs, a faulty ignition coil or an engine problem.

Knock sensor circuit breakdown

The knock sensor serves to evaluate spark knock. If a spark knock exists, the sensor generates a voltage signal that is detected by the computer and the check engine light illuminates on. With this failure, you may experience driveability complications such as power output failures and engine hesitation. Possible reasons could be a faulty knock sensor circuit. 

Whenever the check engine light comes on, have an auto mechanic inspect your car immediately.