1. Excessive Fluctuation in Multiple Measurements: If three consecutive measurements taken in the same environment and on the same body part show a fluctuation exceeding 0.3℃, the sensor sensitivity has decreased, resulting in unstable readings. Replacement is recommended.
2. Large Standard Deviation: If a reading consistently exceeds 0.5℃ compared to a calibrated medical thermometer (or a brand-new, qualified electronic thermometer), and calibration fails to improve this, the device has developed irreversible accuracy issues and needs replacement.
3. Hardware Malfunction: If, after replacing the battery, the display remains blank, blurry, or has missing digits, or if the probe is deformed from impact or water damage, these hardware malfunctions are usually irreparable and replacement is recommended.
4. Exceeded Service Life: The service life of a reputable, qualified product is generally 3-5 years. Inferior, low-priced products used for more than 2 years, even without immediate noticeable abnormalities, indicate that the core sensor has aged, compromising accuracy. Replacement is recommended.
