Navien water heater error E110

What causes E110

The air intake or exhaust is blocked.

What to do

Check the vent terminations outside for blockages.

Can I fix it myself?

You can make the first check yourself, but stop there: this code can point to a serious fault.

If the code comes back

Book a visit and add the code to the booking. A technician arrives knowing which parts to bring, diagnoses the water heater for a flat $89 and gives you an exact quote before doing any work.