Boiler intermittently displays E030 and stops heating

Safety first: Turn off power before working on low‑voltage sensor wiring.

• Step 1 – Locate outdoor sensor: Find the outdoor temperature sensor mounted on an exterior wall, away from direct sun or exhaust vents.
• Step 2 – Inspect wiring: Check the cable from the sensor back to the boiler for cuts, staples through the wire, or UV damage. Repair or replace as needed.
• Step 3 – Check connections: At the boiler control board, ensure the outdoor sensor wires are firmly attached to the correct terminals.
• Step 4 – Replace sensor: If wiring is intact and E030 persists, replace the outdoor sensor with a Navien‑approved part.

If the system allows, you can temporarily disable outdoor reset in the control menu to restore operation until the sensor is replaced.