Digital thermometers provide quick, accurate temperature readings, but their displays sometimes show cryptic letters instead of numbers. These non-numerical readings can cause confusion when trying to determine a body temperature quickly. Understanding these codes is important because they communicate information about the device’s function, the measurement environment, or the placement of the probe. This guide clarifies what these status codes mean and what actions you should take when they appear.
Understanding Non-Temperature Readings
The display of “POS” is not a universal error code but is specific to certain brands, most notably Braun ThermoScan ear thermometers. On these models, “POS” stands for a “Position Error,” meaning the device’s infrared sensor failed to get a stable reading. This occurs when the probe is not inserted snugly into the ear canal or if it moves during the brief measurement process. The device prevents an accurate calculation of the core body temperature by interpreting the lack of consistent thermal equilibrium as an unstable position.
If your model is not an ear thermometer, “POS” could be a proprietary code unique to that manufacturer. It might also be a misinterpretation of a different, more common code, such as “LO” or a partial display of a longer error message. The device may also be indicating a pre-measurement state, prompting the user to place the probe in the correct position before initiating the temperature scan. Consulting the specific device manual is the most reliable way to confirm the meaning of any non-standard display.
Common Thermometer Status Codes
Many digital thermometers share standardized codes to communicate measurement limits or malfunctions. The code “LO” appears when the temperature being measured is below the device’s minimum detection threshold. For body temperature thermometers, this often means the ambient temperature is below approximately 90°F (32°C), indicating the probe is not correctly placed in the body. Conversely, “HI” displays when the detected temperature exceeds the maximum limit, which is typically around 109°F (43°C) for most consumer models. These limit codes signal that the measurement is outside the operational temperature range.
Another common message is “ERR” or a series of dashes (—), which signifies a general system malfunction or incomplete reading. An “ERR” code can be triggered if the temperature reading is interrupted or if the internal sensor is too warm before the measurement begins. This can also be caused by internal damage, such as moisture intrusion or a shorted probe. Some models may also flash the °C or °F symbol to confirm the temperature scale currently in use.
Steps to Take After Seeing a Code
When a non-temperature code appears, the first step is to address the most common causes of measurement failure. If you see “POS” or “ERR,” check the probe placement and ensure the contact is stable and secure before attempting a new reading. For ear thermometers, ensure a new, clean probe cover is correctly attached and the lens is free of earwax or debris. Allowing the device to reset for a minute by turning it off and back on can sometimes clear a temporary software glitch.
Next, evaluate the device’s power source, as a low battery can trigger various error codes even if a dedicated low-battery indicator is not present. Replacing the batteries with fresh ones is a simple troubleshooting step that resolves many display issues. If the thermometer was recently exposed to a significantly hot or cold environment, allow it to stabilize for up to 30 minutes at room temperature to ensure the ambient conditions are within its operational range. If the code persists after these steps, the device may have an irreversible internal fault and require replacement.