Renault Trafic 2017 1.6dci DTCC59F/ UO59F 'check anti-polution system'

[Tom050162]

Recently bought a 2017 trafic III with 132k miles on it which has developed a recurring 'check anti-polution system' and engine management light. I attempted resetting it with a generic OBD2 scanner which worked initially, but it comes back straight after startup once it has been started 3 times.

Have monitored cat temps and it is completing DPF regens as normal. However fault keeps coming back so keep clearing it every few days.

Decided to get a proper scan with a snap on zeus which pulled a few error codes with U059f - Invalid data recived from NOx sensor "B" pointing to faulty sensor. Cleared it with the snap-on, however it came back again. Replaced NOx sensor 2 with a genuine unit however, when cleared it returns as pending DTC, then current after 3 starts.

Sp far i have done in same order :
- Cleaned pressure sensor pipe in engine bay as it was blocked (no symptoms however)
- tested NOx sensor plugs with a multimeter (12v on supply, 2.4v on can low and 2.6v on can high, low resistance on ground wire so all good at the plugs)
- Replaced downstream NOx sensor with genuine part
- Replaced the MAP sensor as this looked to be reading incorrect, however, new sensor exact same values.
- removed and cleaned adblue injector (wasn't too crusty)

I added a 1.5L bottle of adblue and level went up from 80% to 92% so seems as though all is well with the level sensor. Took it on a long drive around the m25 and monitored the cat temps which have been reaching >600°c suggesting it is successfully completing active regen. Soot loading is low <5%.
Any help or suggestions would be much appreciated, really struggling to work anything out.

I wonder if the snapon scanner is wrongly referring to the upstream NOx sensor as position 2/B, when in fact the fault is with the upstream sensor?

Thanks,

Tom.