Shut down of return sensor T2
Check the data in Error mode. Boiler data during error:
1 Error = 31
2 Operational status = 00
3 Flow temp. = 230
4 Return temp. = xx*
5 kW burner = 00**
6 % pomp = xx*
* = variable values
**= x3415=BTU/hr
Check the wiring. check the wiring for the sensor