Beetle 1.6 BFS 2002 rough idle smokey/ fault code 17925 vagcom /p0138 crypton act 11

Beetle 1.6 BFS 2002 rough idle smokey/ fault code 17925 vagcom /p0138 crypton act 11

Hi a little advice if possible - am chasing a rough idle fault / rich running fault on Beetle - vagcom showing power supply to ecu fault on relay j271 or j363 - wherever it is?!
my old crypton act11 is showing p0138 high voltage on post cat o2 sensor - have checked vac pipes etc - not experienced with vagcom am using an older version but as cars a lot older than the software assume it is up to the job - engine sounds sweet as a nut when revved / started from cold - mileage 113k
any thoughts or direction to pursue the issues would be very helpful, thanks Terry