W202 722.6 Transmission Going into Limp Home Mode

[w202wraith]

I have a 99 C280, and its transmission seems to go into 'limp home' mode at random times, perhaps a couple of times per week. If I turn off the engine and restart, it ususally returns to normal. I have recently changed the transmission oil, but it has been happening prior to the fluid change.

A quick search on this forum revealed that it might be a 'sensor plate' that could cause this problem. Is this the correct diagnosis? How much does it cost to replace it at the dealer or a shop? Can this be a DIY? If so, what parts should I get, and what is the procedure?

Thank you in advance,
w202wraith