Emissions light on 1.6 fsi

[Anchco]

got an emissions light on took it to the garage and they pluged in the computer and found it were a NOX sensor that popped up, bought a new NOX sensor and had it fitted after about 10-15miles the light popped up again, i took it back to the garage, it was a different fault code but still was to do about the NOX and apparently the NOX control module is prone to collecting water so he cleaned the water out did a cheak around the wires, another 10-15miles it pops up again and this made us both clueless on whats wrong with it.
does anyone have any ideas on whats wrong with it?
Thanks

[Crasher]

We need the fault code number that is has now.

[Anchco]

the engineer gave me bit of paper with some details on which are;

NTK
o3c907807c
NOX control box
20/04


i don't know if o3c907807c is the fault code

[Crasher]

That is the part number, we need the fault code.