Gather the sensor datasheet, a multimeter, and a known reference thermometer
Disconnect power to the sensor circuit if required by the manufacturer
Inspect the sensor and wiring for damage, corrosion, or loose connections
Measure the sensor resistance or output signal at room temperature
Compare the reading to the expected value in the datasheet
Place the sensor and reference thermometer in the same temperature environment
Test at multiple temperatures, such as ice water, room temperature, and warm water
Record the sensor reading at each test point
Compare each reading to the reference temperature
Check for sudden jumps, drift, or unstable readings
Verify the sensor output changes smoothly as temperature changes
Test continuity of wiring and connectors if the sensor does not respond
Replace the sensor if readings are outside the specified tolerance