Speed sensor

[mikeG82]

Hello,
My ML 270 2004 was seen at the garage for not going above 3rd gear (auto) the fault code was P2203- speed sensor 3 faulty and P220a speed sensor implausible, they were not keen to fix, I have tried to find the part but can’t seem to find new. Any idea what I actually need? And where speed sensor 3 is located?
Thanks

 

[ajlsl600]

It seems like the sensor that recognises 3rd gear eng rpm( or trans output shaft rpm) requires a change up, is not functioning and the ecm therefore does not signal 3rd gear clutches to disengage and 4th gear clutches to engage, however I don't know if the speed sensors are on the intrans plate I suspect so. Tho someone else will be along. Suggest you check all trans harness connections and run diagnosis again save fault codes then try delete codes see what happens if it's still an active fault it won't clear. If so I suspect an internal electronic plate fault.
Wait for others. I have limited experience on benz trans, conductor plates or the speed sensors involved
Someone will be along