Have a problem with Stagea RS4 Auto gear box
 

Have a problem with Stagea RS4 Auto gear box refuses to change into top.
No overdrive as well, light works but no change in speed or revs.
Has had small issue with late changing but now will not change into top at all on throttle or off down hill or up.
Has any one had any issues like this any ideas how to start?
Have an idea it could be water related as washed engine bay night before
Is there any connectors Etc that are in the engine bay that could cause this.
No fault codes on ECU showing??
Help please