Mercedes Check Engine Light

Reasons Behind Your Mercedes’ Check Engine Light Turning On


By Bavarian Performance Specialists February 14, 2020

Your Mercedes is a complex machine with hundreds of parts and systems. When a component starts to fail, your vehicle will often let you know by displaying warning lights which can help you to respond accordingly to the problem presented. The most severe and the most tricky warning system to diagnose is the check-engine light, which is found on your dashboard. Let’s take a closer look at the reasons behind this warning light and learn some of the top reasons why your Mercedes might be detecting an issue.

What does the Check Engine Light mean?

Also known as the Engine Management Light (EML), unlike other warning lights, the check engine light doesn’t tell of a specific fault. Instead, it is designed to alert the driver to a variety of more serious issues which can affect your engine’s functions, such as emission trouble.

The EML is connected to the ECU (Engine Control Unit), which is your Mercedes’ main computer. If it notices one of the systems connected to the engine or the exhaust are showing errors, the ECU will trigger the warning light.

When it comes to what to do when the light illuminates, there can be several options. If your car still feels like it is running fine, then you can carefully drive it to a professional repair shop. However, if your car is challenging to drive or you’re in a higher-risk driving environment, such as the motorway, then pull over and call for roadside assistance.

Reasons Behind Check Engine Light Illumination in your Mercedes

As previously mentioned, there can be a whole range of reasons why the check engine light is illuminated. Below, we’ve listed some of the top culprits as well as their risk factor and how to respond to the issue.

MAF Sensor

Damage risk: Low
Response: Drive to your nearest repair shop at a reduced speed.

The MAF sensor (also known as the Mass Airflow sensor) is a sensor which is responsible for measuring the amount of air which enters the engine. Too little or too much airflow can negatively impact the operation of your engine, causing rough idling or poor acceleration. Issues with the MAF sensor can be caused by filter blockages which is why it is important to replace the filter every few years as part of good maintenance practices.

O2 Sensor

Damage risk: Low
Response:  Drive to your nearest repair shop at a reduced speed.

Also known as the oxygen sensor, the O2 sensor is responsible for measuring oxygen quantities that enter and exit the engine. If this part notices deviation from healthy parameters it will inform the ECU which will cause the check engine light to illuminate.

Ignition System

Damage Risk: Medium
Response:  Drive to your nearest repair shop at a reduced speed.

The ignition system is in charge of the ignition stroke of the combustion cycle and makes sure that the air and fuel mixture inside the engine is ignited correctly. If your Mercedes is a gasoline model, then you could develop an issue with the spark plug timer or the ignition coil. This will cause misfire which will ruin engine performance and could even damage your catalytic converter.

Catalytic Converter

Damage Risk: High
Response:  Drive to your nearest repair shop at a reduced speed.

The catalytic converter is an essential part of all vehicles, and alongside the engine, it is one of the most expensive parts to repair and replace. Its primary role is to clean up your vehicle’s emissions converting toxic gases into those which are safer. The converter can become damaged as a result of failures in other systems such as the EGR valve, which could cause unburned fuel to ignite inside the converter, causing severe and expensive damage. If this problem is what is causing your check engine light to illuminate, you’ll need to resolve it ASAP.

Bavarian Performance Specialist

If your Mercedes is displaying a warning light, Mercedes Ignition Coil Replacement or you’ve been caught out by sudden illumination and need diagnostic information, then come to Bavarian Performance Specialist of Thousand Oaks, Agoura Hills, Westlake, Malibu, and Newbury Park, CA. Our friendly team of experts will be able to inspect and resolve your problem quickly, preventing any further damage from being done to your car, meaning you can drive away happy.

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