Navien error codes explained for San Jose homeowners
Navien tankless heaters report faults as E codes. A few of them account for most service calls, and knowing what they mean helps you decide what to do next.
- 4 min read
- San Jose focus
- Sept 2026 updated
Perfect Tankless Plumbing, San Jose, CA
The most common Navien tankless codes are E003 for ignition failure, E012 for flame loss, E016 for an overheated heat exchanger, E030 for exhaust overheating and E515 for a control board abnormality; owners can safely check gas, power, filters and venting, while repairs inside the unit need a plumber.
How Navien codes work
Navien tankless and combination units display three-digit E codes on the front panel. Each code maps to a fault the control board has detected, from ignition to venting to the board itself. Navien's condensing design also depends on a working condensate drain, which adds a few causes other heater types do not have.
As with any brand, the code says what the unit detected rather than the root cause. E003 means the burner never lit, but the reason might be the gas supply, the air intake filter or the igniter.
E003 and E012: ignition and flame
E003 is ignition failure: the unit tried to light and never confirmed a flame. It is the most common Navien code. Check that the gas valve to the heater is open and that other gas appliances work. In cold weather, a blocked vent termination can also stop ignition.
E012 is flame loss: the burner lit and then went out during operation. Gas pressure that drops when other appliances run, a dirty intake air filter and worn ignition parts are common causes. If either code returns after one reset, call a plumber.
E016: overheating
E016 means the heat exchanger is overheating. In hard-water homes, scale is the usual cause, because a coated heat exchanger cannot transfer heat into the water fast enough. A clogged cold water inlet filter or low flow can contribute too.
The fix is a descaling flush through the service valves and a clean inlet filter. If E016 keeps returning, flushing more often or adding a softener usually stops it.
Navien showing an E code? Call and read it to us. We will tell you what it likely means before we come out.
Call (669) 281-0871E030: exhaust temperature
E030 means the exhaust is running hotter than it should. The cause can be the venting, the heat exchanger or the exhaust temperature sensor. Check the vent termination outside for blockages, but leave the vent connections and sensors to a plumber.
Because exhaust problems involve combustion gases, an E030 that returns is a reason to stop using the unit until it is checked.
E515: control board
E515 indicates an abnormality in the control board. Before assuming the board has failed, a plumber should check the unit's grounding and wiring, because a poor ground can produce the same code.
If the board has failed, it is replaced and the unit's settings are restored. That is a repair, not a reason to replace the whole heater.
What you can check, and what to leave
Safe owner checks: the gas valve is open, power is on, the intake air filter and cold water inlet filter are clean if your model allows access, and the vent termination outside is clear. Inside the unit, including the burner, igniter, sensors, fan and board, is a job for a plumber.
Reset once after checking those things. If the code returns, call rather than resetting again.
From the guide to the job
Services related to this guide
Navien Tankless Water Heater Repair
Ignition and flame loss, Overheating and scale.
How we handle navien tankless water heater repairTankless Descaling and Flush
Isolation valve retrofit, Inlet filter cleaning.
Read about tankless descaling and flushWater Softener Installation
Salt-based softener, Salt-free conditioner.
Water Softener Installation
FAQ
Questions readers ask about this
E003, ignition failure.
Usually scale in the heat exchanger. A descaling flush normally clears it.
No. Check grounding and wiring first.
Reset once after basic checks. If the code returns, call a plumber.
Rarely. Most point to a repairable cause such as gas supply, scale, venting or a single part.
More guides
Keep reading
Hard Water and Your Water Heater in San Jose, CA
What the local hardness numbers mean for tanks and tankless units, and what helps.
Read the guide on hard water and heatersRinnai Error Codes Explained: 10, 11, 12, 16, 79 and LC
What the common Rinnai codes mean, what you can check yourself and when to call.
Rinnai error codes
One number, any hour
E code still showing?
Call and read us the code. We will tell you what it likely means and bring the right parts.
