Sub-Zero E3 Error Code Explained
Short version: E3 usually points to the evaporator thermistor (temperature sensor) or the wiring/connection in that thermistor circuit. The control board is seeing an evaporator temperature signal that’s out of range or inconsistent.
What E3 Means
A Sub-Zero E3 error code typically indicates a problem with the evaporator temperature sensing circuit. In most cases that’s the evaporator thermistor itself, but it can also be a loose connector, damaged wiring, corrosion, or (less commonly) a control board input issue.
Safety First
- If you’re removing panels or inspecting wiring, disconnect power to the unit first.
- Model layouts vary. If your unit’s steps differ, follow the Sub-Zero service manual for your exact model.
Quick Troubleshooting Steps
1) Try a reset
- Many Sub-Zero units allow an alarm/reset by holding the “alarm” bell button for about 15 seconds.
- If E3 returns quickly, continue below.
2) Check the thermistor connection
- Locate the evaporator thermistor connector (often near the evaporator/coil cover area depending on model).
- Look for a loose plug, corrosion, bent pins, or damaged wiring.
- Reseat the connector firmly and recheck the error.
3) Look for conditions that can affect readings
- Heavy frost/ice buildup can affect airflow and temperature readings.
- Check that doors seal properly and vents aren’t blocked.
How to Test an Evaporator Thermistor
A common method is measuring thermistor resistance with a multimeter at a known temperature. A standard reference point is an ice-water bath (32°F / 0°C).
- Disconnect power (recommended).
- Disconnect the thermistor from the harness/control circuit.
- Place the thermistor tip in an ice-water bath long enough to stabilize.
- Measure resistance across the thermistor leads with a multimeter.
Typical reference: Many Sub-Zero evaporator thermistors read approximately 30,000–33,000 ohms at 32°F (0°C). If your reading is far outside this range, reads open/infinite, or is unstable, the thermistor is likely faulty.
Note: Thermistor specs can vary by model and sensor type. If you have the Sub-Zero service sheet for your exact model, use its stated values as the final reference.
When to Replace the Thermistor (and When to Call Service)
- Replace the thermistor if resistance is out of range/open or E3 persists after confirming the connector/wiring.
- Call a service technician if:
- E3 returns immediately after a known-good thermistor is installed
- wiring/harness damage is suspected
- cooling performance is poor or multiple faults occur
Common Parts Related to E3
- Evaporator thermistor / temperature sensor
- Thermistor wiring harness / connector
- Control board (less common)
Helpful Links
- Shop Sub-Zero OEM Parts
- Sub-Zero Error Codes & Troubleshooting
- Where to Find Your Sub-Zero Model & Serial Number
Need Help Identifying the Correct Part?
If you’re not sure which thermistor or related part matches your exact Sub-Zero model/revision, we can help you confirm the correct OEM part before any charge or shipment.
Informational only. For model-specific procedures, consult the Sub-Zero service manual or a qualified technician.