Humidifier or dehumidifier shows incorrect humidity readings compared to a separate hygrometer.

Safety: Unplug before opening the housing.

• Clean sensor area: Gently brush dust from the humidity sensor and surrounding vents.
• Relocate unit: Ensure the appliance is not placed in a corner or behind furniture where air is stagnant.
• Offset settings: If the Philips model allows, adjust the target humidity to compensate for a known offset.

For large discrepancies, the humidity sensor module should be replaced to restore accurate control.