Navien E441: hot water sensor 2 fault

Navien heaters use several temperature sensors to control the burner and mix water to your set temperature. E441 is a fault in one of the hot water sensors, which the manuals call sensor 2.

The meaning below comes from Navien's manuals for its NPE condensing tankless water heaters. Navien directs owners to its technical support line (1-800-519-8794) or a licensed installer for this code.

A note on the name

Navien's NPE-A user manual describes E441 as hot water inlet 2, while other Navien manuals list it as hot water outlet 2. Either way, it is a hot water temperature sensor with an electrical fault, and the repair is the same.

Common causes

• A loose, wet or corroded connector
• Damaged wiring to the control board
• A failed sensor

The repair

After checking the wiring, a technician measures the sensor and replaces it if it reads open or shorted. The part is inexpensive.

How to reset a Navien

1. Close all hot water taps.
2. Turn the unit off with the power button on the front panel, wait about a minute, then turn it back on.
3. Open a hot tap and watch whether the code returns.

Before you call

Have the model and serial number from the rating label ready, along with the exact code and when it appears: at startup, during use, or only at high demand. Mention any recent work on the gas, water or electrical supply and when the heater was last descaled. This helps the technician bring the right parts and often saves a second visit.

See every code on our Navien error codes page.