Your car is a Kompressor so it does not need the map sensor, it uses a charge air sensor instead. They use the same wiring loom for both models as this works out cheaper than making two different looms.
see diagram of all sensors on the SLK (post face lift).
2 pressure sensors
1 for manifold (sensor B28)
1 for ambient pressure (sensor B18).
from your pics this is sensor B18. this sensor isnt critical it only helps with adjusting a/f ratio when starting car (i.e. making it a bit richer or leaner). after the car has warmed up it serves no purpose.
the other sensor DOES matter... it influences peformance and activation of the cam shaft adjuster.
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