Sensor Monitoring Data Is Inaccurate

Use this guide when a Sensor reading does not match the expected value or another instrument.

Visual troubleshooting flowchart

Troubleshooting steps

1. Compare the same conditions. Compare readings at the same time and in the same location. Allow the Sensors to stabilize before judging the difference.
2. Check the environment. Door openings, defrost cycles, vents, cooling coils, frost, and uneven shelf temperatures can cause real differences.
3. Run a side-by-side test. Place two Sensors of the same model together for 24-48 hours. If one Sensor clearly follows a different curve, record both SNs and contact support.
4. Use compensation carefully. Check the model's measurement range and accuracy. Use compensation only for a confirmed fixed offset, not for changing environmental patterns.

Optional checks at home

These checks can reveal a problem at one temperature or humidity point. They do not verify accuracy across the Sensor's full range or replace a comparison with a calibrated reference instrument.

• Temperature (immersion-rated probes only): Fill an insulated container with crushed ice and just enough clean water to fill the gaps. Keep plenty of ice in the container. Place only the probe tip in the ice-water mixture, away from the container walls and bottom. Once the reading stabilizes, compare it with 32°F (0°C) and the model's stated accuracy at that temperature. Do not immerse a Sensor body, connector, or probe unless its specifications allow it. See NIST's ice-point verification guide.
• Humidity (models that measure relative humidity only): Put a small dish of table salt in an airtight container. Add a little water so the salt is damp but some solid salt remains visible. Place the Sensor or humidity probe above the dish without touching the salt or liquid. Seal the container and keep it at a steady room temperature, away from sunlight, until the reading stops drifting; this can take several hours. Saturated sodium chloride produces about 75% RH near 77°F (25°C). Compare the stable reading with the model's humidity accuracy, allowing for temperature and home-setup variation. See ASTM E104 and Vaisala's saturated-salt guidance.

The saturated-salt setup above checks humidity in the air above the solution; it does not buffer a refrigerator probe's temperature reading. Salt solution can also provide thermal mass, but direct liquid buffering requires a probe rated for immersion and a separate sealed setup. A buffered reading responds more slowly to brief air-temperature changes; it does not verify Sensor accuracy. See CDC guidance on buffered temperature probes.

Do not change compensation from a single home-check result. If the difference remains large, contact support with the test conditions and readings.

When contacting support, provide the Sensor SN, model, comparison period, deployment environment, and placement photos.