Terex ta 25 zf trans codes

HI hef working on a terex truck torque converter bearing went bad leaking oil. Boys a centrans rebuilt our torue new trans pump and supplied bearings. After assembling short test drive code pops up Lil wrench and a gear that says stop. I check fluids wires ect. Unhooked battery cable and gave the Lil wrench 10 mins. Hooked battery cable up and code comes instant. I dont think lil wrench means it's fixing itself lol. Code is( bf ) operation manual says mechanical fault or speed sensor and that's it. I'm hoping someone can supply some info or where to get some thanks

Terex ta 25 zf trans codes