Why is my engine warning light on?

The Engine Warning Light can be one of the most confusing warnings in your dashboard cluster because it offers no explanation as to why you should check your engine. It could be as serious as a malfunctioning gear box or as minor as a loose gas cap.

What is the Engine Warning Light?

The engine warning light also known as the ‘Check Engine Light’ or ‘Engine Management Light’ — more formally known as the malfunction indicator lamp — is a signal from the car's engine computer that something is wrong.

What does it mean when the engine warning light is flashing?

If your engine warning light is flashing while you're driving your vehicle is not safe to drive. Avoid heavy acceleration and high engine speed. Stop the vehicle when it's safe to do so. You should get it checked as soon as possible.

How does the Engine warning light work?

The Engine Warning Light location and colour will vary for each vehicle, but in most cases it is located on the dashboard, is yellow and shaped like an engine. It may also have the words “check” or ‘engine” integrated into the design.

What are the common reasons the engine warning light will come on?

• Oxygen Sensor malfunction (emissions issue)

If your vehicle has a malfunctioning oxygen sensor, it could run irregularly or sound rough when it idles. A faulty oxygen sensor can impact your engine's timing, combustion intervals, and other essential functions. You could also notice stalling or slow acceleration.

• Loose or faulty petrol filler cap

The filler cap is part of the vehicle’s evaporative emissions system and can cause problems with the system if it has an issue. An improperly sealing fuel cap may cause an evaporative system leak, which will set off the Check Engine Light when the computer detects the leak.

• Catalytic Converter issues

The Catalytic Converter is in the line of the exhaust between the engine and the silencer. Its purpose is to reduce emissions from the exhaust with an efficiency level required to control pollution. The check engine light will come on if it’s below this threshold, determined by oxygen sensors that are located before and after the catalytic converter.

• Faulty spark plugs/wires/ignition system

Common signs of failing spark plug, wires or ignition system include a decrease in power, acceleration, and fuel efficiency. In addition, the engine light coming on or visible damage to the cables can be signs of a failing wire.

• Vacuum hose leak

A common sign of a vacuum leak is a hissing sound coming from the engine area while the vehicle is running. Other signs include accelerator problems or an idling speed that is faster than it should be.

• EGR valve failure

A faulty EGR valve can cause problems with the flow and operation of the EGR system leading to performance issues including a reduction in power, reduced acceleration and decreased fuel efficiency.