DAF XF 105 460: AdBlue System Warning, Power Limitation, and Exhaust System Errors

Hello, the car displays the error: Exhaust system warning (also the exhaust indicator light is on), then limits the engine power.
In the autocom, it easily reads the exhaust gas temperature before and after the catalyst, while NOX concentration sensors (before and after) display the message: Not ready or inactive.
One more parameter puzzles me, whose screen is included in the attachment.
Bez tyt...png Download (182.76 kB)

Gentlemen, generally where to start, or how to diagnose it so as not to spend a fortune on it ??
I will be grateful for any hint.

Start by reading the error codes.

Sorry for the honesty, but you take the diagnosis without knowing what to expect.
The NoX sensor does not generate a nox signal until the temperature of the NoX sensors exceeds 350 degrees Celsius. So, realistically, an engine gassed at a standstill until death, will never create such a temperature of exhaust gases that NoX sensors generate a signal with NoX concentration in real time.
As the previous speaker said, enter active error codes.

Mistakes:
Bez tyt...jpg Download (79.31 kB)

It turns out that noxy to exchange.

You can help a little before spending a fortune, clear mistakes, make a 15 km route by car, and read the errors, in the meantime check
fuses,
disconnect plug from pump pump spray to improve contact reconnect plug, check the battery from the frame side if there is no green coating in the plugs, if there are visible pins in the Nox sensor and inside the plug.
Each diagnostic program - I have never used it before - has a tab with system process activations, e.g. air supply, activation of the adblue dispenser, etc.
In general, you can have two nox sensors to replace - but first the beam to check. pump - sensors.

Just after clearing the errors and driving about 15km errors appear again. I eat today and check the plugs. So if nothing gets better, NOXs need to be replaced

Replacing the sensors solved the problem.