Sub-Zero 600 and 700 Series Code 06: Refrigerator evaporator sensor error

What 06 means

Legacy 600 Series units such as the 650/F and 700 Series models like the 736TCI show code 06 when the refrigerator evaporator thermistor has been open or shorted for 10 seconds or more, or reads erratically. This sensor watches the temperature of the refrigerator coil. When its signal cannot be trusted, the control loses track of the coil, and owners may see frost on the back wall or uneven fresh-food temperatures.

Common causes of 06

Refrigerator evaporator thermistor open or shorted
Damaged wiring near the refrigerator evaporator
Loose connection at the board

✓ One safe check you can try

1. Note code 06. 2. Look for frost buildup on the back wall of the fresh-food section. 3. Turn the refrigerator's breaker off and on again with a two-minute pause. 4. Check temperatures with a thermometer over the next day. 5. Call us if the code returns or frost grows.

! Why to stop there

The evaporator sensor sits behind the evaporator cover.
Testing needs a meter and correct reference values.
Ice around the sensor must be melted safely, never chipped.

Opening a panel yourself does not automatically cancel a manufacturer warranty, but it can cause accidental damage, and some manufacturers set their own service conditions. Check your warranty terms, or ask us, before deciding.

→Same appliance

Other Refrigerator codes

23Sub-Zero 600, 700 and 648PRO Code 23: Defrost overheat with no feedback 50Sub-Zero 600 and 700 Series Code 50: Refrigerator compressor running too long 41Sub-Zero 648PRO Code 41: Zone compressor or wiring problem 81Sub-Zero 700-2 Code 81: Variable-Speed compressor fails to start 82Sub-Zero 700-2 Code 82: VS compressor controller needs replacement 88Sub-Zero 700TF Code 88: Board and compressor controller not talking 80Sub-Zero 700TF Code 80: No inverter feedback after a board change ddSub-Zero 600 and 700 Series Display dd: Diagnostics switched off

0606 questions

Code 05 or code 06, which sensor is which?

05 points to the cabinet sensor that reads the air in the fresh-food section, while 06 points to the evaporator sensor clipped near the refrigerator coil. Both are thermistors, but they sit in different places.

Why is frost building up?

The control relies on the coil reading. When the evaporator sensor reports nonsense, the coil can be left to frost over, which then blocks airflow into the cabinet.

What is the repair?

We test the sensor and its wiring, melt any ice safely and replace what tested bad. The price is written down before work starts, and the repair carries a 30-day warranty.