Drove the car in stop and go traffic in 96 degree heat and check engine light came on. Stayed on after several restarts. Then went for a long ride with the top down and made a stop. Got in, started it and light was not on anymore.

Does the heat cause the light to come on? I have an appointment for a service on Monday and they’re going to check it out. Just wondering what I’m getting into with this.

2000 CLK 320 Cabriolet

Thanks!

 

Unless the CEL remains on, as both a pilot and owning my 2001 CLK320 cabriolet since new, I would not be concerned.

The air intake system consists of a filter and mass air flow sensor (MAF) .

The MAF measures the amount of air entering the engine, that the engine control module (ECM) uses to both calculate and adjust the optimal air-fuel ratio, required by the engine.

However, the Earth's atmospheric density changes based on variations in:

-Altitude
-Atmospheric pressure
-Temperature
-Humidity

The composition of dry atmosphere, by volume, is mostly Nitrogen, ~78% which is non-flammable, followed by Oxygen, at ~21%.

Note: A combustible substance can burn and if nitrogen could burn, all life on earth would have been destroyed long ago. Since Nitrogen gas makes up some 78 percent of the earth's atmosphere and roughly 21 percent of the atmosphere is oxygen, if it could combine with nitrogen in a combustion reaction, there would be no oxygen left for organisms (i.e. human) to breathe. Fortunately, that isn't the case.

Oxygen is also non-flammable, but is a high-energy gas that very readily oxidizes other materials. For something to burn, the reaction requires a fuel (i.e. gasoline) and an oxidizer like oxygen.

Basically, the high temperature/humidity you experienced, could have been the temporary culprit, due to exceeding the normal range parameters of the factory air/fuel measuring framework.

I had to replace mine, right after the 5 year/50,000 mile warranty and free A/B services expired. When the dealership installed a new air filter, I discovered that the reason my MAF died, was because the tech left a wrinkle in the filter's rubber surround, that allowed a bit of unfiltered air to contaminate MAF's internal sensor hot/cold elements.

It's important to always replace the air filter or MAF with either genuine MB parts or from the OEM company that manufactures the part for MB. The parts for either procedure, on your CLK320 , are inexpensive and can be replaced in less than 10 minutes time.

 

Thanks for the information! Very interesting and informative. I’m getting Service B performed tomorrow and getting her looked over. They’re going to inspect her as well. So, I should have a pretty good idea of what she’ll need maintenance-wise. She sat in a garage for the most part over the last two years, so I’m sure she’ll need more than just a Service B.