The engine warning light can be one of the most confusing warnings in your dashboard cluster because it offers no specific 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. This light could indicate a number of faults, from minor issues like a failing electrical sensor to a much larger mechanical issue, like a fault with your emission control system or catalytic converter.

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.

Is it dangerous to drive with my engine warning light on?

Yes, it could be dangerous to continue to drive if your engine warning light comes on. You should have your car checked out by a mechanic as soon as possible. If you’re driving when you see the warning light come on, it’s important to remain calm, pull over to a safe area and assess the situation to determine your next step.

Firstly, is the light flashing? This could be a sign of a more serious problem like an overheating engine or engine misfire, sometimes causing irreversible damage. You shouldn’t drive further if this is the case.

What colour is the light? Some vehicles have a yellow engine warning light that indicates a problem should be addressed soon, and a red light to indicate that you should pull over immediately.

Will my car fail its MOT if the engine warning light is on?

Yes, your car will fail its MOT if your Engine Warning Light remains on when the engine has been started. Under the new MOT rules, it is now classed as a major fault.

About Fixter

Fixter is revolutionising the car maintenance industry, one repair at a time. Fixter was founded to make car maintenance as easy as booking a taxi. Digital, transparent and stress-free, with world-class customer service. Since launching in Manchester in 2017, Fixter has expanded to more than 100 towns and cities across the UK and provided thousands of car owners with honest, convenient and affordable car repair services.