Can a car pass MOT with engine light on?

“Can a car pass MOT with engine light on?” is a question we get asked a lot here at B&W Auto Centre. Unfortunately, the answer is usually no. The presence of the engine light indicates that there’s a fault or issue with the car’s engine or emissions system. Which means that it will fail its MOT. In fact, it’s now considered a major fault if the light remains on when the engine has been started. Read on to find out more about your car’s engine light and what to do if it appears. 

What is the car engine light?

The engine light, which some people call the check engine light, is a warning light that sometimes shows up on the dashboard of a vehicle. Typically represented by an image of an engine. This light is there to alert the driver of a potential issue with the car’s engine. 

There are different types of engine lights to look out for. Most commonly, the engine light will show up as a bright, orange light. This indicates a minor problem with the engine. Alternatively, the engine light will blink or illuminate as a solid red light instead of orange. This suggests that the problem with the engine is far more serious and needs addressing immediately. 

What should I do if the engine light appears?

Noticing the engine light on your car’s dashboard can be worrying. However, it may not always suggest a major problem. The cause could be something as minor as a loose fuel cap. If you see a bright orange engine light that isn’t flashing, you may not necessarily need to pull over right away. Since you would usually be able to tell if something was seriously wrong by feeling unusual handling or hearing strange noises from the engine whilst driving the car, it’s normally safe to keep driving. Although, it’s important to get your vehicle inspected as soon as possible so that the cause of the engine light can be identified.

On the other hand, if the engine light is flashing or is red in colour instead of orange, you’ll need to stop your car right away and call your garage immediately to have it removed and inspected right away. This is because these types of engine lights tend to indicate potentially serious problems that could result in major damage to your engine. 

What can cause the engine light to show?

There are various possible reasons why your engine light could be showing. Whilst some can be minor, others are much more serious. The most common reasons for the check engine light appearing on your dashboard can be found below. 

Loose fuel cap

Sometimes a loose fuel cap can cause the engine light to appear. The fuel tank contains valves which stop the vapours from the fuel from escaping. They do this by recirculating fumes back into the tank. If the gas cap is loose, the system will detect a leak, lighting up the check engine light. A loose fuel cap should be the first thing to check for if your engine light has appeared.

The oxygen sensor has failed

Similarly to petrol fumes, the oxygen sensor (sometimes referred to as the O2 sensor) measures the amount of oxygen in the exhaust system. The data from the sensor is sent to the car’s computer, which then uses it to control the amounts of fuel and air that enter the cylinders. However, if the oxygen sensor isn’t working as it should, the engine will burn more fuel. This can lead to damage to the catalytic converters and spark plugs and potentially cause the car to fail the emissions test. 

A faulty or broken catalytic converter 

The catalytic converter is a key component of the exhaust system, helping reduce harmful emissions by converting those harmful pollutants into less damaging substances. If the catalytic converter is damaged, clogged, or fails to function properly, the engine light may appear. Although a catalytic converter can sometimes be repaired, often replacement is necessary. 

Spark plug and ignition issues

Spark plug and ignition issues can be a common cause of the engine light appearing. The ignition coil is essential for igniting the fuel and air mixture within the cylinders. However, if it’s not functioning properly, you’re unlikely to get very far. Worn-out spark plugs can cause your engine to misfire when accelerating, and it could even stop unexpectedly which is obviously very dangerous.  

Dead battery

The check engine light on your car’s dashboard may be illuminated due to a problem with the battery. If the battery has recently been disconnected, the electrics in the vehicle could need adjusting slightly. This is usually a fairly common issue to fix.  

The engine light may also show if:

• There’s been a vacuum leak
• The exhaust gas recirculation valve has failed
• There’s an issue with your aftermarket alarm system 
• The mass airflow sensor has failed 

MOT’s in Rossington 

If you need to book an MOT, look no further than B & W Auto Centre. We offer MOT’s in Rossington, serving motorists in and around the local area. Whilst the answer to “Can a car pass MOT with engine light on?” is no, our mechanics are on hand to find out what the problem is and carry out the necessary work to fix it. We can help get your vehicle through its MOT successfully, getting you back on the road in no time at all.

Contact us

If you’re wondering can a car pass MOT with engine light on or to book your vehicle in for an MOT, service or repairs, get in touch today. You can reach us by calling 01302 969860 or by sending us a message via our website.