Hey blacksheepinc I have a similar problem my heater Ur value goes under 100 and the shield reads 21%o2 then if fluctuates to 174 ur and the readings go to 12%o2 and just bounce between to two values I am trying to figure out what's wrong if you make headway let me know. With the sensor disconnecte...

Thanks for reply! Made it after your schematic, and used your code. After using a new bosch IC, the SPI issue is disappeared. But still, with stone cold sensor UR is around 55, while calibration value show 157. So the analog reading is fine. I have a brand new sensor, but I guess it is faulty someho...

Hello Christian, Actually I have something similar problem. After heating phase(sensor gets hot also), it stops with error message 0xE8FF. Also, if I modify the code it turned out, the the calibrations values are "normal" Ur=173, Ua=303, however when it exists from calibration mode, Ur is ...