Just thought I'd share how I rectified problems with my 1999 W202 over the 5+ years I have owned it. I feel I am obliged to do so after using this forum to help me along.

1. The ABS/ESP light kept coming on intermittently. Stopping the car and restarting fixed it but after a few days same problem. Researched the Net and found that a faulty brake light switch was to blame. (located under the gas pedal). Cost RM100 (USD 25) to fix. All's well now.

I have one.
'99 C280, some display segments on the left side of the climate control module only worked if I pushed on the display. I removed the module, opened the case, and carefully wiggled the large blue connector for the display ribbon cable up and down a couple of times to re-seat the connections. Perfect display ever since
Dan

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2012 E350 Bluetech

Here's another one...
If the battery has been disconnected both the sunroof and the express-up/down feature of the windows may need to be resynchronized. I copied the following from another post;

"al humphreys
The correct procedure to re-synchronize the windows is as follows. With the key on, raise the window up using only the "first" position of the switch..DO NOT press the switch past the resistance point, into the detent position. When the window is up, hold the switch in that position for 5 sec. Repeat the procedure, putting the window down , again using only the "first" position of the switch, do not press past the resistance point, and then hold it down for 5 sec. This should re-synchronize the window. "
This must be done for each window.
The procedure for the sunroof is similar. Open and hold button for more than 5 seconds then close and hold button again.

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2012 E350 Bluetech