Yes you were right it was a leak after all.

There were leaks at pretty much every joint actually. I used exhaust assembly paste and ring gaskets to seal them all.

No engine codes have reappeared yet so I think the issue is resolved. The exhaust is significantly quieter but sounds better imo.

Thanks for all the support. Greatly appreciated

 

Good news and no problem!
If you compare the good readings (sensors) to the error'd sensor, it appeared the sensor is working as were all the other parameters so it pointed to a leak.