Navien Error Code 10 — Causes, Fixes & Prevention in Los Angeles

May 20, 2026  |  Troubleshooting

Navien error code 10 is one of the most common calls we get from Los Angeles homeowners. It indicates an exhaust or intake blockage — and in Southern California, the cause is almost always something specific to our climate and wildlife.

What Does Navien Error Code 10 Mean?

Error code 10 on a Navien tankless water heater indicates that the unit has detected an abnormal exhaust pressure — meaning the combustion gases can't flow out of the unit normally. The unit shuts down as a safety measure to prevent carbon monoxide buildup inside the home.

Most Common Causes in Los Angeles

1. Bird Nest in the Vent Termination

This is the #1 cause of Navien code 10 in LA. House sparrows, finches, and other birds common in the San Fernando Valley frequently build nests in the horizontal vent termination on the exterior of homes. The vent cap looks like an ideal nesting location — it's warm, sheltered, and elevated.

A partial blockage will trigger occasional code 10 errors. A full nest can completely block the vent and prevent the unit from operating at all.

Fix: Inspect the vent termination on the exterior of your home. Remove any nesting material. Install a vent guard with smaller openings to prevent re-nesting.

2. Debris or Leaves in the Vent Cap

Los Angeles wind events (especially during Santa Ana conditions) can drive leaves, seed pods, and debris into vent terminations. This is especially common in fall and early winter.

3. Improper Venting Configuration

If code 10 appears in a newly installed unit or after a recent installation, the vent run may be too long, have too many elbows, or be improperly terminated. Navien has specific venting requirements — exceeding the allowable equivalent length causes code 10.

4. Kinked or Crushed Flexible Vent Pipe

Some installations use flexible vent pipe (not recommended by Navien but still common). These can kink over time, especially if run through tight spaces or if they've shifted after installation.

How to Fix Navien Error Code 10

1. Go outside and locate the vent termination(s) — usually a white PVC pipe on the exterior wall where the water heater is installed
2. Inspect for bird nests, debris, or any visible blockage
3. Clear any obstruction carefully
4. Reset the Navien by pressing and holding the power button for 3 seconds
5. If the code returns immediately, the blockage may be inside the vent run — call us for diagnosis

Preventing Code 10 From Coming Back

The most effective prevention for bird-related code 10 errors is installing a vent guard with a mesh or baffle that prevents birds from entering while still allowing proper airflow. We install Navien-approved vent guards as part of our service calls.

If you're getting code 10 regularly without any visible blockage, the vent configuration may need to be assessed by a technician. Call Simple Water Heater & Filtration for prompt Navien diagnosis and repair throughout Los Angeles.