How do I fix Navien error code 10?

Go outside and inspect the vent cap on the exterior wall where your tankless water heater is installed. Remove any bird nests, leaves, or debris. Then reset the unit by pressing and holding the power button for 3 seconds. If the code returns, the blockage may be inside the vent run and requires a professional technician.

How do I reset Navien error code 10?

To reset a Navien after error code 10, press and hold the power button for 3 seconds until the unit powers off, then press it again to restart. Important: if the code returns immediately after reset, the blockage has not been resolved and the unit needs professional service.

Why does Navien error code 10 keep coming back?

If Navien error code 10 keeps returning after reset, either the blockage has not been fully cleared, or the vent configuration has a problem such as excessive length, too many elbows, or improper termination. In Los Angeles, recurring code 10 is often caused by birds re-nesting in an unprotected vent cap.

Is Navien error code 10 dangerous?

Yes — error code 10 should be taken seriously. It means combustion gases may not be venting properly. The unit shuts itself down as a safety measure to prevent carbon monoxide buildup. Do not attempt to bypass the error. Address the root cause before operating the unit again.

How much does it cost to fix Navien error code 10?

If the cause is a simple vent blockage you can clear yourself, the fix is free. If a technician is needed to inspect the vent run, clear an internal blockage, or reconfigure improper venting, typical service call costs in Los Angeles range from a standard diagnostic fee plus any parts needed. Contact Simple Water Heater & Filtration for a specific estimate.

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

July 5, 2026 | Navien | Los Angeles

Your Navien tankless water heater is showing error code 10 and you have no hot water. This is one of the most common Navien calls we receive throughout the San Fernando Valley and greater Los Angeles — and the good news is that most of the time, you can identify the cause in under two minutes by walking outside and looking at your exterior wall.

What Does Navien Error Code 10 Mean?

Navien error code 10 indicates an abnormal exhaust pressure reading. The unit's pressure sensor has detected that combustion gases are not flowing freely through the venting system. As a safety measure, the Navien shuts itself down to prevent carbon monoxide from backing up into your home.

This is not a fault you should reset and ignore. Error code 10 means your unit is protecting you — and the underlying cause needs to be resolved before the water heater is safe to operate.

Safety First

A blocked vent means combustion gases — including carbon monoxide — may not be escaping safely. Do not repeatedly reset and run the unit without identifying and fixing the cause. If you smell gas or suspect CO buildup, leave the home and call 911 before calling us.

Why Error Code 10 Is So Common in Los Angeles

Los Angeles has a specific combination of conditions that makes Navien error code 10 far more common here than in most other cities:

1. Bird Nests in the Vent Termination — The #1 Cause in LA

This is the cause of the majority of error code 10 calls we receive. House sparrows, finches, and other birds that are extremely common in the San Fernando Valley are attracted to the exterior vent termination on your home's wall. From a bird's perspective, it is perfect real estate: elevated, sheltered from rain, and warm from the exhaust heat.

A partial nest will trigger intermittent code 10 errors — often appearing in the morning when the birds are most active or when the unit first fires. A full nest can completely block the vent and prevent the unit from operating at all.

This problem is seasonal — it spikes in spring nesting season (March through June) but can occur year-round in LA's mild climate.

2. Leaves, Seeds, and Debris from Santa Ana Winds

Los Angeles's Santa Ana wind events — most common from October through March — drive leaves, seed pods, and debris into vent terminations at high velocity. A vent cap that was clear in the morning can be partially blocked by afternoon during a strong Santa Ana. If your code 10 appeared suddenly during or after a wind event, this is likely the cause.

3. Spider Webs

LA's dry climate is ideal for spiders, and the warm exhaust from the vent makes the vent cap an attractive nesting spot. A dense spider web across the vent opening creates enough resistance to trigger the pressure sensor, particularly on cooler mornings when the pressure differential is greater.

4. Improper Venting Configuration

If error code 10 appeared on a newly installed unit, or after any work was done on the water heater or adjacent walls, the venting may be incorrectly configured. Navien has specific requirements for maximum equivalent vent length, number of elbows, and vent termination clearances. Exceeding these limits causes chronic code 10 errors that will not resolve without reconfiguring the vent run.

5. Kinked or Crushed Flexible Vent Pipe

Some installations — particularly older ones — use flexible vent pipe rather than rigid PVC. Flexible vent can kink over time, especially if it was installed with minimal clearance or if something has shifted in the wall or attic where it runs.

How to Find and Fix Navien Error Code 10 Yourself

Before calling a technician, run through these steps. Most code 10 issues in LA are DIY-fixable in under 15 minutes.

Step-by-Step Fix

Go outside and find your vent termination. Look for white PVC pipe(s) coming through the exterior wall near where your water heater is located inside. Most Navien units use concentric (pipe within a pipe) or side-by-side terminations. There may be one pipe for air intake and one for exhaust, or a single concentric fitting.
Inspect the vent cap visually. Look for bird nesting material (grass, twigs, feathers), spider webs, leaves, or any debris partially or fully blocking the opening. Even a partial obstruction is enough to trigger code 10.
Clear any obstruction carefully. Remove nesting material by hand or with a stick. Do not insert anything into the pipe itself — just clear the termination opening. If you find a fully built nest, check whether eggs or chicks are present before removing (birds with active nests are federally protected — if the nest is active, call us and we can advise on timing).
Check the area around the cap for damaged or crushed pipe. If the exterior pipe appears kinked, cracked, or separated from the wall fitting, that is a job for a technician.
Reset the Navien. Go back inside and press and hold the power button on the unit for 3 seconds until it powers off. Wait 30 seconds, then press the button again to restart. The unit will run its ignition sequence.
Test the hot water. Open a hot water tap and confirm the unit fires and produces hot water without returning the error code.

If the code returns immediately after reset: the blockage may be further inside the vent run, or the vent configuration has a problem that requires professional assessment. Call us at (855) 4-HOT-H20.

How to Prevent Navien Error Code 10 From Coming Back

The most effective and lasting fix for recurring code 10 errors caused by birds is installing a properly designed vent guard that prevents birds from entering while maintaining full airflow. Standard vent caps with large openings are effectively open invitations for house sparrows, which are small enough to enter and build a nest inside the fitting itself.

We install Navien-compatible vent guards on virtually every code 10 service call we do in Los Angeles — after clearing the blockage and confirming the venting is correct, adding the right guard prevents re-occurrence in the vast majority of cases.

For debris and wind-related blockages, the vent guard helps here too. Inspect the termination area twice a year — once in fall before Santa Ana season and once in spring at the start of nesting season — as a quick preventive check.

When You Need a Professional for Navien Error Code 10

Call Simple Water Heater & Filtration if any of the following apply:

The error returns immediately after clearing the visible blockage and resetting
There is no visible blockage at the vent termination
The error appeared on a newly installed unit or after recent work on the water heater
The exterior vent pipe appears kinked, cracked, or separated
You smell gas near the unit or vent termination
The error is intermittent and has been recurring for more than a week

We are factory-trained on Navien's full NPE and NPN product lines and carry the parts and vent guards needed for same-day resolution of code 10 issues throughout Los Angeles, the San Fernando Valley, Westside LA, and Ventura County.

Other Navien Error Codes We See Frequently in LA

While you are looking into code 10, it is worth knowing the other codes that are common in Los Angeles due to our hard water and climate:

Error Code 27 — Scale buildup alert. LA's hard water (200–400 mg/L) makes this the second most common Navien code we see. Annual descaling prevents it.
Error Code 3 — Ignition failure. Gas supply issue, dirty igniter, or faulty gas valve.
Error Code 12 — Flame failure during operation. Often related to gas pressure fluctuation.
View all Navien error codes →

Frequently Asked Questions — Navien Error Code 10

Navien error code 10 indicates an abnormal exhaust pressure reading — the unit cannot vent combustion gases freely. It shuts down as a safety measure. In Los Angeles, the most common cause is a bird nest or debris blocking the exterior vent termination.

Press and hold the power button for 3 seconds to power off the unit, wait 30 seconds, then press again to restart. Always clear the blockage first — resetting without fixing the root cause will just trigger the error again, and continuing to operate the unit with a blocked vent is a safety risk.

Recurring code 10 after clearing the visible blockage usually means birds are re-nesting in an unprotected vent cap. Installing a proper vent guard resolves this permanently. If the error returns without any visible blockage, the issue may be inside the vent run — improper length, too many elbows, or a kinked pipe — which requires professional assessment.

Yes — it should be taken seriously. A blocked vent means combustion gases including carbon monoxide may not be escaping properly. The Navien shuts itself down as a safety measure. Do not bypass or ignore the error. Resolve the root cause before operating the unit again. If you smell gas or feel unwell, leave the home and call 911.

If you can clear a simple bird nest or debris blockage yourself, the fix costs nothing. If a technician is needed to inspect the vent run, clear an internal blockage, reconfigure improper venting, or install a vent guard, costs vary by scope. Contact Simple Water Heater & Filtration at (855) 4-HOT-H20 for a specific estimate.

Yes. Simple Water Heater & Filtration provides Navien error code 10 diagnosis and repair throughout the San Fernando Valley including Sherman Oaks, Glendale, Burbank, Encino, Studio City, North Hollywood, Van Nuys, Northridge, and all surrounding communities. We also serve the Westside and Ventura County.