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Why has my engine management light come on?

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If your car engine management light switches on while driving, there's a problem which needs addressing ASAP.

Nobody wants to see that little yellow engine sign lighting up their dashboard. Especially when it's flashing urgently. And while it might be tempting to ignore it for as long as possible, the reality is that you really don't know how serious the fault is until you get it checked out. You never know, it might be something as simple as a loose fuel cap.

If it does come on, you can get a range of estimates from the best local garages using WhoCanFixMyCar. For engine management light diagnostics, just enter your registration number and we’ll do the rest.

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Below you can find the top five things that could cause your engine management light to come on.

Oxygen sensor problems.

Loose or broken fuel cap.

Faulty catalytic converter.

Airflow sensor problems.

Failing spark plugs.

Frequently Asked Questions


Oxygen sensor problems

The oxygen sensor is responsible for monitoring how much fuel is being burned within your car's engine. It does this by examining the level of oxygen in the exhaust system. The most common cause of problems with an oxygen sensor is oil and ash coverage which prevents the sensor from carrying out its primary function.

There are a number of oxygen sensors located within a car engine system, including the exhaust system and certain parts of the combustion system.

If this is the problem, a mechanic can fix it very quickly. However, if you ignore the engine warning light and a blocked oxygen sensor is the issue, the knock on effect could cause huge damage to the catalytic converter and cost upwards of £1,500 in repairs!

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Loose or broken fuel cap

Surprisingly, the engine warning light will switch on if the fuel cap is not closed properly or there is damage on the part which allows air into the fuel system.

Therefore, if the warning light switches on, stop your car and check the fuel cap. If it is secure, take a close look to see if there are any cracks.


Faulty catalytic converter

The catalytic converter is responsible for preventing dangerous fumes like carbon monoxide and other harmful pollutants from entering the air. The catalytic converter is part of the exhaust system. If left untreated, it will pose a risk to you and your passengers, as dangerous fumes could leak into the interior of your car.

Catalytic Converter Diagnostic Quotes


Airflow sensor problems

If there is a problem with the mass airflow sensor or the engine air filter is clogged, the engine light will come on. Fortunately, the fix is very simple and cheap as the air filter can be easily reached and replaced if needed.


Failing spark plugs

Spark plugs are responsible for initiating the combustion process within a car's engine. Your car will struggle to start if one of them is faulty. However, a spark plug is easily replaced and the repair will not be expensive.


Summary of repairs you might need to resolve an engine warning light


If you're still not sure, have a mechanic diagnose your warning light.

With the engine warning light being a bit vague it is possible that your problem won't be anything above, or may be a combination of a couple of them. If you're unsure you can have a mechanic run your car through a few tests to determine and then fix the issue at hand.

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Frequently Asked Questions

Can I drive my car with my engine management light on?

Why does my engine management light keep coming on and off?

Are the engine management light and ECU light the same?

Can the engine management light come on for no reason?

What do the other warning lights mean?


Can I drive my car with my engine management light on?

When you first start your car, the engine management light will flash on for a few seconds to show that it's working. If it stays on while you're driving, this indicates a problem. Fortunately, as long as the light is steady and not flashing, you should be able to drive to a nearby garage to get it checked. If the light is flashing, on the other hand, this signals a more serious problem. In this case, it's best to pull over as soon as it's safe to do so.


Why does my engine management light keep coming on and off?

The answer to this question depends on when the light flashes on and off. It's normal for the EML to light up for a few seconds when you first start your engine, but if it flashes while you're driving, this indicates a serious fault which should be dealt with without delay.


Are the engine management light and ECU light the same?

In a word, yes. Confusingly, there are a few different names you might hear people using that all refer to the same yellow light on the dash. The engine management light, engine control unit (ECU) light and check engine light are all the same.


Can the engine management light come on for no reason?

The only reason this would happen was if your car had some kind of electrical fault causing the light to come on and stay on. This is an unlikely situation, so if you see that little light glowing on your dashboard, it's best to get your car checked by a professional to be on the safe side.


What do the other warning lights mean?

If you want to understand more about warning lights, you can read our guide on what the most common car warning lights mean.

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