U-Line Refrigerator Error Code E6

The E6 error code on a U-Line refrigerator indicates that Thermistor 1 has read a temperature at least 10 degrees Fahrenheit below the set-point for a continuous period of more than 12 hours. Thermistor 1 monitors the refrigerator compartment temperature and feeds real-time readings to the control board. When the board detects a sustained over-cooling condition of this magnitude and duration, it registers E6 as a fault to alert the user and technician that something is actively driving temperatures too low.

The most likely root cause is a faulty relay on the circuit board. A relay in a stuck-closed or welded position can keep the compressor or evaporator fan running continuously without the normal duty-cycling that maintains temperature within range. This results in the refrigerator section dropping well below its set-point and staying there, which is exactly the pattern the 12-hour timer in the E6 logic is designed to catch. Because the relay and the board it is mounted on are closely integrated, diagnosis often points to the board assembly as a whole rather than the relay in isolation.

Additional contributing factors can include a miscalibrated or failing thermistor itself, which could falsely report low temperatures even if actual compartment temperatures are normal. However, confirming a true temperature drop with a secondary thermometer will help distinguish a genuine over-cooling fault from a sensor reporting error. In either case, the control board's ability to accurately process sensor input and cycle components correctly is central to resolving this fault.