On an M103, that sensor can be a pain to get at without pulling the valve cover, but I have done it. You just have to find a deep socket with skinny enough wall. Order a new valve cover gasket if you take the cover off because they are prone to leak.

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-tp


1990 300SE "Corinne"- 145k daily driver - street modified differential - PARTING OUT OR SELLING SOON - PORTLAND OR. AREA - PM ME FOR DETAILS
1988 560SEL "Gunther"- 190K passes anything except a gas station
1997 S420 - 265k just bought it with a rebuilt trans. Lovely condition