Navien E030 Error Code: Exhaust overheating
Updated October 2026 · Sourced from Navien documentation
The exhaust (flue) temperature went above 149 F (65 C) and the water heater shut down. The manual lists cleaning the cold water inlet filter and flushing the heat exchanger.
Is it safe to keep running? No. Turn it off and get it checked. Exhaust overheating involves the flue. Call a licensed technician to flush the heat exchanger and inspect the vent system if it returns.
E030 at a glance
| Code / how it shows | Meaning | Applies to |
|---|---|---|
| E030 Error code shown on the front panel display | Exhaust overheating | NPE-180A2, NPE-210A2, NPE-240A2, NPE-180S2, NPE-210S2, NPE-240S2 condensing tankless water heaters |
Check this first
Only steps a homeowner can do safely. Do not open electrical panels or the burner area.
- Let the unit cool, then clean the cold water inlet filter (manual section 4.4).
- Make sure the water supply valves are fully open.
- Do not run the unit if the code returns.
🛑 Stop and call a licensed pro if
- Exhaust overheating involves the flue. Call a licensed technician to flush the heat exchanger and inspect the vent system if it returns.
- You smell gas. Leave the house, do not touch switches, and call your gas utility from outside.
- Codes for flame failure, overheating, venting or the control board that return after one reset.
- Water leaking from the heater, the relief valve discharging, or scorching around the burner area.
- A carbon monoxide alarm sounds. Get everyone outside and call 911 or the fire department.
Safe first steps for any Navien code
- Write down the exact code shown on the controller or the number of status light flashes.
- Turn the water heater power off and back on (or press the reset button the manual describes) once. If the code comes back, stop resetting.
- Make sure the gas supply valve to the heater is open and other gas appliances in the home are working.
- Make sure the cold water supply valve is fully open and hot water taps are not partly closed.
- Look at the outside vent terminal for snow, ice, leaves or anything blocking it (look only).
Source: Navien NPE Condensing Water Heaters User's Information Manual (NPE-2, rev 201202), 5.2 Understanding Error Codes, p.17. Codes are series-specific, so your unit's own manual is the final word. Reviewed October 2026.
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