Boiler displays OUT or Outdoor Sensor Error; outdoor reset function not working correctly.

Safety first: This is a low-voltage sensor circuit; shock risk is minimal but turn off power before wiring work.

• Check sensor location: The Laars outdoor sensor should be on a north or northwest wall, out of direct sun and away from windows or vents. Relocate if improperly placed.
• Inspect wiring: Follow the two-conductor cable from the sensor to the boiler. Repair any cuts or loose connections. Ensure it is connected to the correct outdoor sensor terminals on the control.
• Compare readings: In the boiler menu, view the outdoor temperature reading and compare to actual outdoor temperature. If it reads -40°F/°C or very high, the sensor may be open or shorted.

When to call a professional: If replacing the sensor and checking wiring does not correct the reading, the control board may be faulty.