Junkers zw 23 ke - does not heat water in the central heating circuit

As the topic. The pump is running. However, the water in the circuit heats up only in the vicinity of the stove and (oddly enough) in the thermo, even though the potentiometer for domestic hot water is set to the minimum. I checked the filters - clean. I drained the CO water, flooded it again, and vented everything possible. No fault code is shown. The stove simply heats up the amount of water in the circuit very quickly, which it deems right and turns off.
Any ideas to check it without calling the service?

Hello, maybe start with the simplest ones, i.e. the filter under the boiler, is it not clogged and the boiler, through the bypass, transfers water only in the boiler?

Is it about the filters marked in the photo? If so - it's already checked.

I would check the circulation pump.
best regards

The pump works on the bank. I wrote.
But I noticed, however, that after the water is heated, the second and third LEDs are lit.

Added after 14 [hours] 5 [minutes]:

I found error codes.
Diode / lamp - 45 degrees protection against overheating has worked.
Diode / lamp - 60 degrees / no signal from the ionization electrode.

But they shine - both. Does it fit with the description I posted?
What else could I do?

To disassemble and clean the black 3-way valve under the pump, but the operation is difficult even for a service technician and you need a new O-ring for the valve.