The model of the car is W218 2016 CLS 220D.
The functionality of my ECO mode ceased earlier this year. I only see the yellow ECO wording on the dashboard and not the green box with inverted writing, indicating that it is not engaged.
Additionally, I observed that the air conditioning system fails to emit cold air even when set to its lowest temperature setting. Furthermore, even when the temperature is set to 20 degrees Celsius, and the surrounding temperature ranges between 18-22 degrees Celsius, I can hear a noise like air passing over the top of a bottle emanating from the vents.
My dealer inspected the air conditioning system and confirmed that there are no issues with it. However, they noted that it does not produce cold air. Instead, it only cools the air to a maximum of 10 degrees below the surrounding temperature. This is peculiar because when I initially acquired the vehicle, it did generate cold air that was capable of numbing your fingers. The same is true for my wife's Nissan Juke.
Regardless, they said that it is the auxiliary battery. I first suspected that a sensor in the heating matrix may be responsible for the ECO mode not meeting the necessary criteria for activation, particularly if it incorrectly perceives that the appropriate ambient temperature has not been reached. However, they were certain that the issue was with the auxiliary battery.
Today, a new auxiliary battery was installed, which incurred a cost of £200 for both the components and service.
I am uncertain about the specific actions they have taken, since the ECO mode remains non-functional and the font colour persists as yellow rather than green.
Upon driving home, which took around 30 minutes, I saw that the start/stop function did not activate even once.
I considered the possibility that I should use the battery for a short period of time to ensure optimal performance, although one would question the need of doing so for a completely new battery. I accelerated rapidly while driving on a divided highway. The object remains yellow and inoperable.
Unsatisfied with having spent £200 for no result... I am further dissatisfied by the fact that they claimed to have resolved the issue, but it is evident that just starting the ignition proves otherwise.
Do you have any suggestions or thoughts?