ERR1 Error Code is caused by the thermistor indicating too hot a temperature. The thermistor is inside the small metallic tube a few inches from the inside top of the cooking box.
I had a 10K ohm potentiometer on hand so I used it to collect some information about the control electronics. After removing the thermistor from the circuit and placing the potentiometer
in the circuit, I was able to capture data on the system. I would set the potentiometer and then record what temperature the system was seeing.
From the graph, the thermistor appears to be 33K at 25 degrees C with a Beta value of 4200. (Thermistors are speced at 25C with a known Beta.)
The thermistor that I pulled from the unit at one point showed a resistance of 110 ohms and at another time 4.9K. It was clearly defective.
By the way, with the original thermistor in the circuit, we could not get the heating element to come on. The ERR1 error code would also appear.
However, when we installed the potentiometer, we could dial in the temperature simulating a working thermistor. With the pot in place, we then could get the
heating element to turn on.
We have ordered a replacement thermistor from DigiKey, part number 541-1205-ND. This is a Vishay part, part number 04T3302JF.
It may not fit in the original tube so we may have to create a replacement tube for the device.