question: how far away does the tdc sensor have to be away from the magnet of the in the from crankshaft pulley?

BACK STORY:I was under the front of the 190e looking for the TDC sensor to see if it was aligned with the rest of the mechanical timing. It was, but I notice that the front sensor was about 1/2 of a inch away from the magnet in the pulley .....it would seem to me that it should be closer ....but crap...you have to pull the water pump pulley and the crankshaft pulley off just to get to it. One of the previous owners stripped the the water pump pulley star head screws (thanks a-hole) so this is going to be interesting. any thought on this revelation!