Navien tankless water heater repair in San Jose
Navien units report faults as E codes on the front display. Most come down to gas, venting, scale or a sensor, and the code tells us where to start.
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Perfect Tankless Plumbing, San Jose, CA
Navien tankless repair in San Jose starts with the E code: E003 is ignition failure, E012 is flame loss, E016 is an overheated heat exchanger, E030 is exhaust overheating and E515 is a control board fault; we test the cause behind the code, repair or descale the unit and confirm it runs correctly.
Updated September 2026
Water Heaters
Reading a Navien E code
Navien uses three-digit E codes. A handful account for most service calls: ignition and flame codes, overheating codes driven by scale, and venting codes on these high-efficiency condensing units. Condensing models also depend on a working condensate drain, which other heater types do not have.
We are an independent plumbing company, not affiliated with Navien, and we service Navien tankless and combination units. We test the likely causes in order, so a clogged filter or closed valve is ruled out before any part is replaced.
Warning signs
Common Navien codes and what they point to
- E003Ignition failure.
- E012Flame loss during operation.
- E016Heat exchanger overheating.
- E030Exhaust overheating.
- E515Control board abnormality.
- Codes that returnA cause that has not been fixed.
Ignition and flame loss
E003 means the unit tried to light and never confirmed a flame; E012 means it lit and then lost the flame during operation. The common causes are a closed or partly open gas valve, gas pressure that drops when other appliances run, a dirty air intake filter, or worn ignition parts. We check gas pressure at full fire with everything else running, clean the intake filter and test the igniter and flame rod before replacing anything. If the code only appears when the dryer or furnace is also running, an undersized gas line is the likely cause, and we size it properly rather than replacing parts that are working.
Overheating and scale
E016 means the heat exchanger is overheating, and in hard-water homes scale is the usual cause. A scaled heat exchanger cannot move heat into the water fast enough, so it runs hot and shuts down. We flush the heat exchanger with descaling solution through the service valves, clean the cold water inlet filter and check flow, then set a flushing schedule matched to your water so the code does not return. If the code has returned more than once in a year, we also look at whether a softener would protect the unit better than flushing alone.
Condensate, venting and board faults
E030 means the exhaust is running too hot, which points to the venting, the heat exchanger or the exhaust sensor. Condensing Navien units also need a clear condensate drain; a blocked line can back up and trigger faults. E515 indicates a control board abnormality, which we confirm by checking grounding and wiring before considering a board replacement, because a loose ground can mimic a failed board. When a board does need replacing, we transfer the unit's settings and test every function before leaving, so a new board is not hiding a different fault elsewhere in the unit.
How the job runs
How a Navien repair runs
- 1
Read the E code
And when it appears.
- 2
Check gas and filters
Valve, pressure, intake filter.
- 3
Check venting and condensate
Clear and correctly sloped.
- 4
Test components
Igniter, sensors, board grounding.
- 5
Repair or descale
Fix the actual cause.
- 6
Confirm operation
Temperature and flow at the tap.
Local context
Hard groundwater and E016
Morgan Hill runs entirely on groundwater from its own wells, with hardness averaging about 267 mg/L, in the very hard range. Homes on supplies like that are where Navien units show overheating codes most often, because scale coats the heat exchanger faster. Annual flushing, and a softener where scale keeps returning, is the most reliable way to keep a Navien out of E016 in the harder parts of the valley.
Included
What our Navien service visit covers
- Code reading and history
- Gas pressure at full fire
- Intake air filter cleaning
- Cold water inlet filter cleaning
- Venting and condensate drain check
- Heat exchanger flush where needed
- Written note of what was found
Cost factors
What a Navien repair costs depend on
We do not publish a local repair price; the cause behind the code sets most of the cost.
- Cause behind the code. a valve, filter or component
- Descaling. a flush versus a part
- Condensate drain. cleared or rerouted
- Venting. blockage or damage
- Parts. igniter, sensor, fan or board
- After-hours timing. emergency visits typically cost more
FAQ
Navien Tankless Water Heater Repair questions from San Jose homeowners
Ignition failure. Check that the gas is on, then call if it returns.
Usually scale in the heat exchanger. A descaling flush normally clears it.
Not always. A poor ground can cause it, so we check wiring before replacing the board.
Yes, including units that also supply space heating.
We're an independent plumbing company that repairs Navien units, not affiliated with Navien.
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From our guides: Navien Error Codes Explained: E003, E012, E016, E030, E515.
One number, any hour
Get your Navien working again
Call and read us the E code on the display. It helps us bring the right parts.
