Boiler displays E13, outside temperature sensor fault on weather-compensated systems.

Safety first: Turn off power before working on control wiring.

• Locate outdoor sensor: The Weishaupt outdoor sensor is usually mounted on a north or northwest-facing external wall, away from direct sun.
• Inspect housing: Check for physical damage or water ingress. Dry or replace the sensor if moisture is present.
• Check wiring: Follow the cable back to the boiler, ensuring no breaks or crushed sections. Tighten terminal screws at the control board.
• Measure resistance: Compare sensor resistance to the Weishaupt curve for the current outdoor temperature. Replace if readings are incorrect.

When to call a professional: If the sensor and wiring are correct but the control still reports E13, the control input may be faulty.