I'm not familiar with that engine...
But I do remember you have a 230E? (Euro?)
If that's an M103 engine, the #1 picture is the 4 pin temp sensor which the previous poster accurately identified as involving the Bosch fuel injection system. The sensor feeds the system info, and your fuel injection system reacts accordingly.
You should also have a two pole, and a single pole temp sensor. The two pole is the ACC emergency cutoff sensor, that kicks in the high aux fans at 105deg?, and shuts off the AC compressor at 115deg to prevent damage.
The single pole temp sensor relays the temp to your dash, and nothing else.
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi