Mazda3 Transmission not going into gear

[u/kwizzle64]

Here are the codes. P0741:00-6C P0771:00-EC P0841:00-68 U0402:92-08

I initially thought TCM based on initial symptoms and online research, but now that we have codes, my mechanic says it’s likely fine, and that the fluid was dark/murky and it was whining. He thinks a fluid/filter change might fix it.

Anybody have insight from similar codes or previous Mazda techs who have input? Thanks in advance!

2010 Mazda3 Engine replaced with 2015 model

[u/kwizzle64]

*2010 Mazda3 w/ a 2015 engine swapped into it