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What does it mean when the Mercedes engine management light turns on?

If your engine management light has come on, it means there is a fault with your car and you should get it checked immediately. It could be one of a number of potential problems and can often be hard to diagnose without proper diagnostic equipment. It is advised to have a mechanic take a look to provide a proper diagnosis.

What would cause the engine management light to come on?

With so many potential issues related to the engine management light, it is useful to have an idea of what it could be.

Oxygen sensor needs replacing

Oxygen sensors perform an important role in feeding information back to the computer that is in your car. The oxygen sensor helps to monitor how much fuel is being burned by measuring the oxygen levels in the exhaust system.

There are generally two to four sensors in each car so any one of them could cause the engine light to switch on if it is compromised.

The sensors will eventually get covered in oil and ash due to their location and as a result, their ability to communicate accurate readings will degrade.

If this is the issue that has caused your engine light to come on, you have got away lightly as this is an easily resolved problem, however, if ignored, you will end up with a serious repair job on your hands.

You could end up having to repair your catalytic converter which could cost well over £1,500 in parts costs alone, never mind the labour cost.

Fortunately, replacing the sensor is easy and can be done by looking in your car owners manual.

The sensors simply clip on and off from their location so make sure to do this at the earliest opportunity if the engine light comes on to rule this potential problem out.

Loose or faulty fuel cap

This may seem like an unlikely reason for the engine light to come on but surprisingly enough, a loose or damaged fuel cap will cause the signal to alert a driver.

Fuel vapor is extremely flammable and any leakage from the fuel tank will also effect the mileage of your car.

That is why it’s essential that you screw the cap on securely every time you finish re-fuelling.

If the cap is secure but the light is still on, check closely for cracks and if you can see anything, have it replaced as soon as possible.

If there is no sign of damage, the issue will likely be one of the others on this list.

The Catalytic converter is damaged

This part makes up a section of the exhaust system and is vital for converting carbon monoxide and other dangerous compounds.

If there is an issue with your catalytic converter then you’ll notice an increase in the fuel consumption of your car and you will not be able to accelerate properly.

This part is mostly susceptible to damage if other parts fail, such as the oxygen sensors and spark plugs.

If the part stops working, deadly carbon monoxide will be emitted from your car and you’ll be putting the lives of others at risk.

If the part fails then it will need to be replaced. Your fuel consumption will drop dramatically and is one of the most obvious signs that it needs replacing.

The Mass Airflow Sensor

The light in your car will switch on if the mass airflow sensor becomes faulty or breaks, however, it is possible to drive despite the part failing.

The engine light will come on if the air filter on the airflow sensor isn’t properly installed or needs replacing. You should be replacing the filter at least once a year to ensure the sensors work properly all the time.

The MAS (Mass Airflow Sensor) is an important part of the car engine. But it can be faulty and not have a hugely detrimental effect on the car.

However, that doesn’t mean that you should ignore the issue as this could lead to a bigger problem.

Replacing the air flow filter is a relatively simple job so it should not be an expensive or time-consuming job for a mechanic.

Failing Spark Plugs

If the engine light comes on and you have checked all the above, the final thing you should check is your spark plugs.

Spark plugs are in place to initiate the combustion in the car when it starts.

If they are failing, then you should notice some jolting when you accelerate.

Fortunately, spark plugs are relatively simple to replace and are cheap to buy brand new.

A mechanic will take no time at all when replacing the failed parts and this is a job that you may be able to do yourself, though we wouldn’t recommend it unless you have a good understanding of a car’s engine.