Your complaint is mostly about an engine light? Daimler owns both Mercedes and Freightliner which brings me to my point. I drive a Freightliner class 8 truck and there always seems to be an engine shaped yellow light on. This is not to be confused with the engine shaped yellow light which says "Check" on it. Now in the "old days" if you got an engine light you had a problem. Well, according to the shop mechanics, these days it's not always the case. Seems everything in the truck runs through the computer. Example: the radio send a signal to the computer which sends it to the speaker. I have a dead stereo speaker because the truck needs to go to the dealer to get the computer re-flashed. If you turn the wipers on the switch tells the computer to turn the wipers on. What happens is unused circuits/connections cause false signals at times. IF all you have is a yellow light it can just mean you have a "cab fault" and not an "engine code". Frustrating but basically information overload.
If you turn the key towards on (don't start, just wake up dash)and wait for the dash to sequence through, then turn it off and repeat 3 times it will clear some codes.
X2 on the OBD diagnostic tool.
2012 Sundance 3100RB w/Reese Goose Box
2004 Ford F350 6.0 L PSD, CC, DRW, long bed, B&W drop ball hitch, Firestone Ride-rite air bags.