Servicing for farm vehicles

What Does the Check Engine Light Mean on My Dashboard?

When you first jump into your car and switch on the ignition an array of lights will spark into life on your dashboard. Usually, all of those lights will then disappear when you crank the engine and it starts. Consequently, you may not pay any attention to them any more, except when something like the check engine light flickers into life. But what does this really mean?

What's Going on?

The check engine light (which has a symbol that looks like the shape of an engine) is known as a malfunction indicator light, or MIL. When this illuminates it means that the central computer has recorded a diagnostic trouble code, or DTC, indicating a particular problem.

While there can be a number of potential issues at the heart of the problem, these are the five most likely.

Failing Oxygen Sensor

You have an oxygen sensor that needs to be replaced. This type of sensor records how much oxygen enters the exhaust system on your car. This needs to be regulated for overall efficiency, as otherwise you're going to burn a lot more petrol than you need to. In this case you would suffer from poor fuel economy and damage can be caused to the catalytic converter in some circumstances.

Where's Your Petrol Cap?

Secondly, this sensor could indicate something as simple as a petrol cap that hasn't been reattached properly. The cap is there for a reason, as it stops toxic petrol fumes from being emitted into the atmosphere, but it can also help you conserve fuel by prohibiting evaporation.

Faulty Catalytic Converter

The sensor may also indicate that the catalytic converter needs to be changed. This component converts carbon monoxide (which is harmful) into carbon dioxide. It must be maintained periodically otherwise it won't perform correctly, leading to higher operating temperatures and lower petrol economy.

Airflow Sensor

The check engine light may also mean that the mass airflow sensor has to be replaced. This sensor checks how much air is entering your car's engine so that the amount of petrol used is adjusted accordingly for maximum efficiency. This sensor is also there for a secondary reason, as it protects other components such as the catalytic converter and spark plugs from damage caused by incorrect mixtures.

Faulty Spark Plugs

You may also find that you spark plugs need to be replaced, as they are no longer able to provide the necessary ignition spark in order to ignite the fuel/air mixture in the engine.

In most, but not all, of these circumstances you need to schedule a visit to a mechanic. After all, you should be able to replace the petrol cap yourself!