The check engine light didn’t come into existence until 1996 when the federal government required an on-board vehicle diagnostics system for all new vehicles sold in the United States. One of the most important lights on the dashboard is the Check Engine Light (CEL).
The check engine light of your Mercedes is either amber or yellow colour and it represents the engine’s health. It is an integral part of your vehicle’s computer’s onboard diagnostics system. If the light refuses to go off after a few seconds of starting your car, then it means something is off with the performance of your engine. When you notice that the light remains on or is blinking, you should be proactive and consult a professional mechanic to inspect your vehicle to find the root cause of the problem.
There are several reasons why your check engine will stay illuminated. Let’s take a brief look at some of the reasons responsible for the illumination of your check engine light.
- Sagging gas cap: The gas cap of your Mercedes plays a vital role in maintaining pressure in the engine and preventing fuel vapour leakage. Hence, your check engine light will come on if your car’s gas cap is not tightened. Loosen the gas cap entirely and screw it again, but this time, securely. If not, the overall performance of your vehicle will reduce and your engine may begin to misfire due to improper fuel ratios.
- Contaminated oxygen sensors: Suppose the oxygen sensor of your Mercedes becomes contaminated with ash and dust. In that case, it reduces its efficiency, which will lead to a drastic reduction in gas mileage and an increase in gas emissions.
- Dirty or faulty mass airflow sensor: The function of the mass airflow sensor is to alert the computer of your Mercedes of the amount of fuel needed compared to the amount of air entering the engine. When it becomes faulty or covered in dust, it increases gas emissions from your car’s engine, causing the check engine light to illuminate.
- Faulty spark plugs: Spark plugs wear and tear over time. If they start failing, misfires will occur, and the check engine light will come on to alert you.
- Dead battery: The battery of your Mercedes is the primary power source for many of your electrical components. When your alternator becomes defective or fails, the battery will not get enough charge and may cause the battery to run down. The low charge will cause the check engine light to illuminate.
- Faulty catalytic converter: The catalytic converter of your Mercedes functions as a gas converter. It reduces exhaust fumes by converting carbon monoxide and other harmful gases into harmless gases. If it fails, your car will fail its emission test, and your check engine light will come on.
What to do if your check engine light stays on
First, never ignore any warning indicator on your dashboard. When you bought your vehicle, hopefully you flipped through your owner’s manual to discover what each indicator on the dashboard means. Study it thoroughly to have a good understanding. However, if you notice the check engine light of your vehicle has remained on, here are few things you can do before taking it to the mechanic:
- Check the gauges and other lights of your Mercedes for other signs.
- Drive at a slower speed and reduce vehicle load to reduce engine demand.
- Tighten gas caps and check if your check engine light will reset itself. If it doesn’t, call the attention of a mechanic immediately.
Have your check engine lights diagnosed at Turning Wrenches
The engine of your Mercedes is a very intricate system 
which requires the skilled expertise of professional technicians. If you’re a Mercedes owner in the Louisville, KY area and need professionals to handle your maintenance and repair, then Turning Wrenches is just the place for you.
At Turning Wrenches, we are passionate about ensuring that European cars get nothing less than high-quality services. All our mechanics are ASE-certified with decades of experience in repairing any fault in your Mercedes. We employ only state-of-the-art tools for our repairs. By the time we are done with your repairs and maintenance, you’ll be confident of getting it back on the road safely. Call or visit our repair shop to make an appointment with our professionals.