H2
Tristar
Humidity / Steam Sensor Error (sensor-equipped models)
Microwave shows H2 and will not start; may occur immediately on power-up.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Failed humidity sensor, Contaminated sensor lens with grease or steam residue, Loose sensor wiring, Control PCB sensor circuit fault
How to Fix / Troubleshooting
Safety: Unplug the microwave before accessing internal components.
Steps to address H2:
- 1. Clean the cavity: Wipe down the interior, especially near the steam/humidity sensor window (often on the top or side of the cavity). Remove grease and residue.
- 2. Power reset: Unplug for 5 minutes, then plug back in and test sensor-based cooking modes. If H2 reappears, continue.
- 3. Locate humidity sensor: Remove the cabinet and locate the small sensor module near the cavity wall with a small opening into the cavity.
- 4. Inspect and reseat connector: Ensure the sensor connector is firmly attached to the wiring harness and control board. Reseat if necessary.
- 5. Replace sensor if needed: If cleaning and reseating do not help, replace the humidity sensor with the correct Tristar part. If H2 persists, the control PCB sensor circuit may be defective.
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Repair Difficulty
Medium
3/5
Required Part
Humidity Sensor
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