What exactly is triggering error code dE on this appliance? Every few days this error code appears on my display, however the refrigerator is working OK. I can reset the code only by unplugging my refrigerator and then it is gone for a few days. After 2-3 days it appears again. The manual tells only to call for service and does not explain what is causing this to happen.

Thanks. You are correct that about after 48 hrs the code appears again after I reset it. So measuring the defrost heater for continuity as well measuring the termostat should identify the culprit. At what temperatures should the defrost thermostat start opening and closing (opening meaning resistance high, closing resistance zero) or can I not check that with a normal ohmmeter that way ?

Both Defroster and Thermistor look OK. When I reset by unplugging, the defrost cycle is working, meaning it defrosts. I also hear de sissing sound when the unit is defrosting. The symptoms are that as long as the error code dE is displayed, the unit does not defrost at all, but after resetting (unplugging power) the unit defrosts normally.

Should I suspect the defrost timer ?

OK. Today I as able to observe that while the dE error code was displayed, the unit defrosted normally, as indicted by the hissing sound in the freezer, during a defrost cycle.
So that rules out the timer as well, and only leaves the electronic circuitry, sensors etc. Is there a schematic available of these control board and circuitry? It might be a bad capacitor leaking current or so,

Or would you reccommend replacing the board completely?

So this is end of life for this refrigerator then, after only about 7 years ? Ignoring the error code is the only way to go from here?

Is the sensor actually on the board, or separate, and is the board integrated with the display or is there another board?

Final question, since this part is no longer available, are there any places to search for a used part?

Thanks !