Error code C1204

[sirtrojan]

One of our Polish FXer got problem with his 45.
The error C1204 occurred and trans went into service mode.
Any ideas?
What should be check/replaced first?

thank you for your assist!

PS.
Iv found this thread ///11428&highlight=C1204
but its for IInd gen.

 

[StuLax18]

I doubt they would change their codes.

There's also this, but no replies: http://forums.nicoclub.com/code-c1204-on-a-2004-g35x-t449222.html