Navien E030 Error Code: Exhaust Overheat

What you'll notice with E030

• Vent pipe feels much hotter than usual
• Unit shuts down during heavy use
• Often follows years without a flush

What causes it

Heavy scale, a fouled heat exchanger, or improper combustion/venting.

Safe steps you can take right now

1. 1Turn the unit off and let it cool.
2. 2Look for anything blocking the exhaust termination outside.
3. 3Call for service rather than resetting repeatedly — high flue temperatures can damage venting.

How we fix E030

High flue-gas temperature means heat isn't transferring into the water — heavy scale, a fouled exchanger, or a combustion and venting problem. We flush and inspect the exchanger, verify vent sizing and material, and re-test flue temperature after the repair.

Flush and descale, clean the exchanger, verify combustion and vent sizing, and re-test flue temperature.