Boiler shows E16; outdoor reset not functioning correctly; temperatures not adjusting with weather

Safety: Turn off power before working on low‑voltage terminals.

• Locate sensor: Find the NTI outdoor sensor on an exterior north or northwest wall, away from direct sun and vents.
• Inspect wiring: Check the cable for damage and ensure it is connected to the correct outdoor sensor terminals at the boiler.
• Test resistance: Disconnect the sensor and measure resistance; compare to NTI’s temperature/resistance chart. Replace if out of range.
• Relocate if needed: If the sensor is in direct sun or near exhaust vents, relocate to a more suitable location.