P2000-00 NOx trap efficiency below threshold + Oxygen sensors

Hello,

2015 1.6 CR TDI CXXB O3

I had an issue when I bought the car roughly around 217k km P2000-00 NOx trap efficiency below threshold, after I deleted the code it did not came back for long time.. at 224k the DPF were cleaned + EGR also, sadly after that I did not look for the root cause.

At 250k mileage I initiated to check the injectors, 04L130277D 2 were totally out of tolerance so I bought 4 new ones, coding was successfull.. around 251k I had the code again P2000-00 NOx trap efficiency below threshold bank1.

I started to look after the NOx sensor but this car does not have, the sensors around the dpf are: 2 temp sensors 2 diff pressure sensors (03N906051B) and 2 oxygen sensors (03L906262A).

Right now when I delete the failre code it comes back after 150kms.. there is no MIL light that's the funny thing!

I checked the O1S1 and O1S2 sensor values, at the start O1S1 has the voltage of 1.8-1.9V O1S2 is mostly 0.277V, but sometimes jumping to 4.93V (03L906262A original sensors).

After 10-15kms both sensors are stuck somewhere from 1.75V - 1.95V and e.g. O1S1 showing 1.857652 the O1S2 sensor showing the same value exactly!

I ordered an used oxygen sensor to check if it is a sensor issue, whats the limit here for O1S1 and O1S2?

Can it be both sensors are broken and because they are inside the window theres no MIL light?

What kind of an issue triggering P2000-00 NOx trap efficiency below threshold bank1?

I checked under the car there is no NOx sensor installed on this car.

Thank you for your help.