Boiler displays E006 and stops heating, often associated with low temperature readings or sensor error

Safety first: Turn off power and allow the boiler to cool before touching sensors or piping.

• Step 1 – Power cycle: Turn off the boiler for 30 seconds and turn it back on to see if E006 clears. If it returns, continue.
• Step 2 – Locate outlet sensor: Remove the front cover and locate the outlet water temperature sensor (thermistor) on the hot water outlet or heat exchanger outlet manifold.
• Step 3 – Inspect connection: Unplug the sensor connector and check for corrosion, moisture, or bent pins. Dry any moisture, clean gently, and reconnect firmly.
• Step 4 – Check wiring: Follow the sensor wires back to the main PCB, looking for cuts, pinches, or burn marks. Repair or replace damaged wiring.
• Step 5 – Replace sensor if needed: If the error persists, replace the outlet thermistor with a Navien‑approved part. Shut off water, relieve pressure, remove the old sensor, install the new one with appropriate sealing, and check for leaks.

If replacing the sensor does not resolve E006, the main PCB may be misreading the sensor and should be tested by a technician.