Display shows E3; interior light and display work but compressor does not run or runs erratically.

Safety first: Unplug the wine cooler before removing the control panel or top trim.

Steps to address E3:

• Locate ambient sensor: On many Siemens wine coolers, the ambient NTC is located behind the control panel or in the top/front area of the cabinet, sensing room temperature.
• Remove control panel trim: Carefully pry or unscrew the front control fascia. Avoid damaging the touch controls or display ribbon cable.
• Inspect sensor and wiring: Look for a small probe or plastic-encased sensor connected by two wires. Check for discoloration, broken insulation, or loose connectors.
• Test the sensor: Disconnect the sensor and measure resistance at room temperature. Compare to expected NTC values or to another identical sensor if present. Replace if open or shorted.
• Clean connectors: Use contact cleaner on the sensor plug and the control board socket if there is oxidation.
• Replace ambient sensor: If readings are abnormal, install a new ambient temperature sensor (NTC) specified for Siemens wine coolers.
• Reassemble and test: Refit the control panel, restore power, and verify that E3 clears and the compressor cycles normally.

If E3 remains, the display/control PCB or main PCB may be defective and should be evaluated by a technician.