Hoshizaki Refrigerator Error Code E02: Defrost Thermistor Failed
E02 on a Hoshizaki Steelheart A-Series refrigerator or freezer means the defrost thermistor has failed. The appliance cycles 5 minutes on and 5 minutes off. Silence the alarm with the up button, then call a qualified service technician.
Medium: the appliance keeps running on a fixed pattern, but frost can build and the cabinet may warm.
- Code
- E02
- Maker
- Hoshizaki
- Equipment
- Reach-in refrigerators
- Applies to
- Steelheart A-Series upright controller
What does Hoshizaki error code E02 mean?
The defrost thermistor sits on the evaporator and tells the controller when frost has cleared, so a defrost can end at the right moment. When it fails, the controller logs E02 and sounds the alarm. The manual says the appliance then cycles 5 minutes on and 5 minutes off. That fixed pattern keeps it running, but the defrost can no longer be timed to actual conditions. A freezer, which builds more frost, is the more exposed of the two. Frost can build faster than the pattern removes it, and airflow over the evaporator drops until the cabinet warms. Pressing the up button silences the alarm, though the defrost thermistor stays failed. The manual lists the failed defrost thermistor as the cause and says to call a qualified service technician, so this is not an operator repair. A thermometer in the cabinet is the best way to watch the appliance until the visit.
Affected models and control systems
Steelheart Upright A-Series: R1A and R2A refrigerators and F1A and F2A freezers, with the DT2A also named in the manual.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- E02 on the control display
- Alarm that sounds until silenced
- Frost building on the evaporator or back wall
- Cabinet temperature slowly rising
Possible causes
Listed in Hoshizaki's documentation
- Failed defrost thermistor
Other likely causes — what usually sits behind error code E02 on this control. A technician confirms which one it is before any part is replaced.
- A thermistor lead damaged by ice or defrost heat
- Corrosion at the evaporator-side connector
- A control input that does not read the defrost thermistor
Safe checks before calling for service
- Press the up button to silence the alarm.
- Watch a separate thermometer in the cabinet over the day.
- Do not chip frost off the evaporator or use a heat gun.
- Move food if the cabinet warms and note the model and code for the service call.
How a technician diagnoses error code E02
- Confirm the code and check for E01 as well.
- Inspect the defrost thermistor lead and connector at the evaporator.
- Measure the thermistor resistance against evaporator temperature.
- Check the connector and the controller input if the thermistor is normal.
- Replace the thermistor after the measurement and force a defrost to confirm.
- The defrost thermistor is on the evaporator, behind panels and next to refrigerant lines.
- A proper test needs a meter and temperature-resistance values.
- Forcing frost off with heat or tools can damage the evaporator.
How error code E02 differs from similar codes
E02 is the defrost thermistor with a 5-minute on and 5-minute off pattern; E01 is the cabinet thermistor.
Technical reference
- Maker documentation
- Hoshizaki owner support
- Edition
- Number 73237, issued 2-25-2019, revised 3-24-2022
- Models / control
- Steelheart A-Series upright controller
- Section
- Alarm Safeties, Alarm Signals table, pp. 30-31
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related Hoshizaki reach-in refrigerator error codes
Why does it cycle 5 minutes on and 5 minutes off?
The manual says that is how the appliance runs after the defrost thermistor fails.
Is frost a sign of E02?
It can be, since defrost can no longer be timed by temperature. Do not chip it off.
Can I leave it running?
It may keep cooling, but watch the temperature and arrange the service call.
Need help with Hoshizaki error code E02?
A technician confirms the cause on site and gives you the price in writing before any work starts.