2001 C240 W203 45k Miles

Went to check out a C240 45k miles, no CEL but a bunch of MB specific codes revealed via iCarsoft. What got my attention was a code 146 pic below. While stopped tranny shift wasn't entirely smooth. How serious is this code and what does it point to?

No picture.

Code is probably not major if the problem is ATF seeping into the TCM and/or a bad conductor plate (the rpm sensor is in the conductor plate). Conversely, that’s probably all that’s wrong. You’ll need SDS or a similarly sophisticated code reader to clear the codes after correcting the problem. A generic OBD scanner will clear OBD codes but not module level codes... which you appear to have access to with the iCarsoft so you’re set.

Sixto
98 E320s sedan and wagon

The OP's icarsoft will clear the code.

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CENSORED due to not family friendly words