Navien Tankless Repair
Same-day Navien tankless repair in San Jose for ignition failures, flow errors, no hot water, and inconsistent temperature. We diagnose the fault code first, then repair with correct Navien parts so your warranty stays intact.
Certified Navien Service Specialist · San Jose, CA
Navien Tankless Water Heater Service in San Jose, CA
Same-day Navien repair, installation, descaling, and error-code diagnostics across San Jose and the South Bay by a certified Navien Service Specialist. CSLB #1008381.
- Navien Service Specialist
- ·Licensed CSLB #1008381
- ·Bonded & Insured
- ·Same-Day Service
- ·Since 1997
Quick Answer
Efficient Water Heaters, Inc. is a certified Navien Service Specialist providing same-day Navien tankless water heater repair, installation, descaling, and error-code service in San Jose, CA and the South Bay. Call (408) 470-0191 or send photos of your unit for a fast phone estimate. Licensed CSLB #1008381, serving Santa Clara and San Mateo Counties since 1997.
Factory Certified
Navien Service Specialist
Rinnai PRO
Noritz Certified
CSLB #1008381
Bonded & Insured
What we do
Navien Tankless Services in San Jose
Repair, installation, descaling, and diagnostics performed only by water heater specialists.
Navien Tankless Installation
Certified Navien NPE-2 series installation with proper gas line sizing, stainless venting, condensate neutralization, and recirculation planning. Clean, code-compliant installs permitted and finished by a water heater specialist.
Navien Descaling & Flush Service
Annual Navien descaling built for San Jose hard water, restoring flow rate and heat exchanger efficiency. We add isolation valves and descaling filters where the original installer left them out.
Navien Error Code Diagnostics
Professional diagnosis of E003, E012, E016, E030, E110, E407, E438 and every other Navien fault code. We read the unit's history, test gas, venting, and sensors, and explain the cause in plain language.
Navien Recirculation & NaviLink Setup
Built-in recirculation pump configuration, NaviCirc valve setup, and NaviLink Wi-Fi troubleshooting. We tune schedules and comfort settings so you get hot water fast without wasting gas or water.
Navien Replacement & Upgrades
Replace an aging tankless or a failing tank unit with a high-efficiency Navien NPE-A2 or NPE-S2 condensing model. Honest sizing based on your fixtures, gas supply, and venting path — no upsells.
Not sure which service you need? A specialist will tell you in 5 minutes.
Call (408) 470-0191Diagnostics
Navien Error Code Reference
Most Navien error codes point to gas supply, venting, scale buildup, or sensor issues — here's what each one means and how we fix it in San Jose.
| Error Code | What It Means | Common Cause | What We Do |
|---|---|---|---|
| E003 | Ignition failure — the unit tried to fire but no flame was established. | Gas supply off or undersized, low gas pressure, failed igniter, or blocked venting. | Verify gas pressure under load, inspect igniter and flame rod, check venting, replace failed components. |
| E004 | False flame — the control board senses flame when the burner should be off. | Wet or damaged flame rod, wiring short, or a faulty gas valve holding open. | Test the flame rod and harness, inspect the gas valve, and replace the faulty part with Navien-specified components. |
| E012 | Flame loss — the burner lit, then flame was lost during operation. | Gas pressure drop with other appliances running, dirty burner, or exhaust restriction. | Measure dynamic gas pressure, clean the burner and air intake filter, and clear vent restrictions. |
| E016 | Overheating — the outlet or heat exchanger temperature exceeded safe limits. | Scale buildup in the heat exchanger, restricted flow, or a failed temperature sensor. | Descale the heat exchanger, verify flow rate and filters, and replace out-of-spec sensors. |
| E030 | Exhaust overheat — flue gas temperature is abnormally high. | Heavy scale, a fouled heat exchanger, or improper combustion/venting. | Flush and descale, clean the exchanger, verify combustion and vent sizing, and re-test flue temperature. |
| E109 | Abnormal fan operation — the combustion fan is not running at commanded speed. | Failing fan motor, debris in the blower, or a wiring/board fault. | Test fan feedback signal, clean or replace the fan assembly, and confirm normal combustion afterward. |
| E110 | Air pressure / exhaust blockage — combustion air or exhaust flow is obstructed. | Blocked intake or exhaust termination, excessive vent length, or clogged air filter. | Inspect and clear terminations, verify vent length and slope, clean or replace the air intake filter. |
| E351 | Water-related sensor fault on the recirculation/return side. | Failed or shorted temperature sensor, damaged harness, or scale on the sensor probe. | Ohm-test the sensor, inspect wiring, descale or replace the sensor, then verify recirculation temperatures. |
| E407 | Water sensor abnormality — the unit reads an out-of-range water temperature signal. | Faulty inlet/outlet thermistor, connector corrosion, or scale-coated probe. | Test and replace the affected thermistor, clean connections, and descale if scale is present. |
| E438 | Clogged air filter — the intake filter needs cleaning or replacement. | Dust, lint, or garage debris loading the intake air filter. | Clean or replace the air filter, check the install location for dust sources, and reset the unit. |
| E515 | Abnormal operation of the control board (PCB). | Board fault, power supply irregularity, or moisture/corrosion damage. | Verify supply voltage and grounding, inspect for moisture damage, and replace the PCB when confirmed failed. |
| E782 | Communication error between the unit and a control, remote, or cascaded unit. | Damaged communication cable, loose terminals, or a failed remote controller. | Trace and re-terminate the comm wiring, test the controller, and replace failed components. |
Seeing a code not listed? Call (408) 470-0191 for same-day diagnostics.
Try this first
How to Reset a Navien Tankless Water Heater
A reset clears the display, not the fault. Work through these five steps before you call — if the code comes back within a day, the unit has a real gas, venting, sensor, or scale problem that needs a Navien Service Specialist.
- 1
Check the display and write the code down
Note the exact error code shown on the Navien control panel — E003, E016, E030, and E110 all point to different systems. The code tells a specialist which test to run first.
- 2
Confirm gas, water, and power are on
Verify the gas valve at the unit is open, the service switch is on, the breaker has not tripped, and no other gas appliance in the house is out. A closed valve after unrelated work is a common cause.
- 3
Press and hold the reset button
Hold the power/reset button on the front panel for about three seconds until the display clears, then release. Some models require turning the unit off and back on at the service switch instead.
- 4
Run a hot tap and watch the burner
Open a hot fixture for two minutes. The unit should fire, hold a steady outlet temperature, and show no code. Cycling between warm and hot usually means scale on the heat exchanger.
- 5
If the code returns, stop and call a specialist
A code that comes back within 24 hours is a real fault, not a glitch. Repeated resets on an ignition or exhaust fault can be unsafe — call (408) 470-0191 for same-day diagnostics in San Jose.
Code came back after the reset? That is a real fault — get same-day diagnostics.
Call (408) 470-0191Specialist, not a general plumber
Why a Navien Service Specialist Matters
Navien-certified diagnostics
Factory training, correct Navien parts, and warranty-safe repair procedures. We fix the cause behind the code instead of resetting the display and hoping.
Specialist focus
Water heaters are our entire trade — not a side job between drain calls. That means faster diagnosis, cleaner installs, and fewer return visits.
Owner-led by Joseph J. Castro
You talk to a specialist, not a call center. Send photos of your unit and data plate and get a phone estimate — no high-pressure upsells.
Hard water country
Navien Descaling & Flush Service in San Jose
San Jose and the Santa Clara Valley are served by hard water, and every gallon that passes through a tankless unit leaves mineral scale behind on the heat exchanger. Scale insulates the exchanger, forcing longer burn cycles, dropping flow rate, and triggering overheat and exhaust codes like E016 and E030.
Annual Navien flush and descaling service protects efficiency, extends the life of the unit, and keeps documented maintenance on file for your Navien warranty. Where the original installer skipped them, we add isolation (service) valves and a descaling filter so future tankless maintenance in San Jose takes minutes instead of hours.
- Full circulation descaling with manufacturer-approved solution
- Isolation valve retrofit and descaling filter installation
- Inlet screen, air filter, and combustion check included
- Flow rate and outlet temperature verified before we leave
Signs your Navien needs a flush
- Hot water that swings between warm and hot during a shower.
- Reduced flow at fixtures compared with last year.
- Rumbling or a louder burner cycle than normal.
- Repeat E016, E030, or E110 codes on the display.
- No descaling performed within the past 12 months.
Coverage
Navien Models We Service
Navien NPE-A2 Series
Advanced condensing models (up to .95 UEF) with ComfortFlow® built-in recirculation pump and buffer tank — repair, descaling, and installation.
Navien NPE-S2 Series
Standard condensing models up to .96 UEF — the highest-efficiency Navien tankless line we install and service in San Jose.
Navien NPE-A / NPE-S (1st gen)
Original condensing series, including NPE-240A, NPE-210A, and NPE-180S — full repair, parts, and descaling support.
Navien NHW-AI / NHW-AE Series
Non-condensing Advanced interior and exterior models with ComfortFlow® recirculation and NaviTech™ stainless heat exchanger.
Navien NHW-SU / NHW-SE Series
Compact non-condensing universal and exterior units — common on retrofits with limited venting options.
Navien NPN-U / NPN-E Series
Non-condensing universal and exterior tankless — diagnostics, 3" x 5" concentric vent checks, descaling, and replacement.
Navien NCB Combi Boilers
Combination space heating and domestic hot water units — service, repair, and controls troubleshooting.
Navien NWP500 Heat Pump Water Heater
Hybrid heat pump water heaters up to 4.0 UEF — an all-electric option when gas or venting is a problem.
NaviLink Wi-Fi Module
Setup, pairing, firmware, and connectivity troubleshooting for remote monitoring.
NaviCirc Recirculation Valve
Installation and tuning for fast hot water without a dedicated return line.
Navien specs that matter on a service call
- Condensing NPE-2 series reaches up to .96 UEF; non-condensing Navien models run .80–.82 UEF, versus .54–.72 for a gas storage tank.
- Navien is the #1 selling gas tankless brand in North America (condensing and non-condensing, per BRG).
- Condensing Navien units vent in PVC; non-condensing models require 3" x 5" metal concentric venting.
- Navien dual stainless steel heat exchangers carry a 15-year residential warranty when installed and maintained correctly.
- Navien recommends annual service on condensing tankless units — critical on Santa Clara Valley hard water.
- ComfortFlow® models include a built-in recirculation pump and buffer tank, which eliminates cold-water sandwiches.
We service all Navien tankless models, including discontinued units.
What the 2027 Bay Area Rule Means for Navien Tankless
BAAQMD Rule 9-6 changes how gas water heaters can be sold in the Bay Area: gas-fired tank units are affected first, starting in 2027, with gas tankless units following later, in 2031. High-efficiency condensing Navien tankless heaters remain installable now, so if your unit is aging, this is a good moment to talk with a specialist about timing rather than waiting for a failure.
How it works
Four Steps to Hot Water
Send a photo of your data plate for a faster estimate — no high-pressure upsells, ever.
- 1
Call or send photos
Text or upload a photo of the unit, data plate, and any error code on the display.
- 2
Phone estimate
A specialist reviews the model and symptoms and gives you a clear estimate by phone.
- 3
Same-day window
We schedule an arrival window, often the same day, 24 hours a day, 7 days a week.
- 4
Certified repair + cleanup
Warranty-safe repair or install with Navien parts, tested on site, and the work area left clean.
Send a photo of your data plate for a faster estimate.
Get Phone EstimateIn their own words
What South Bay Navien Owners Say
“Had a great experience with the guys at Efficient Water Heaters. Joseph and his employee came out right on time, got to work with no fuss, and a little more than three or four hours later we had a brand new tankless installed in our house. They even swept up the garage cleaner than it was before they got there. Great communication before, during, and afterwards. Would definitely recommend them.”
“I asked a lot of questions about tankless. Joseph was quick in responding and the answers were unbiased and helpful. Marco helped us install the water heater. He is efficient, professional, and the job was very well done. Price is fair — I got the best quote comparing with 2 other vendors who have good reviews on Yelp. Highly recommend.”
“We were in a bind. Had no water and couldn't get ahold of anyone on the weekend. Joseph responded immediately. Scheduled an appointment the next day and gave us a beautiful new tankless hot water heater for the same price as the previous person quoted for a 40-gallon. His work was very nicely done and we are very happy with our new efficient water heater.”
“I'm so pleased with these guys. Very quick to pick up the phone, and got us scheduled right away for our new tankless water heater. The technician Marcos was super friendly and very receptive to some tough design challenges. It was important to me that the pipes were hidden in the walls, and he really went the distance to get it right, including working a very long day to install everything.”
“We texted EWH at 10pm and they called us right away! Our 10-year-old tankless water heater wasn't heating, and Marcus came out first thing the next morning. He had to order parts which came in the next day. He was back quickly to replace them and had our heater back to working. We are very impressed with this company — they are definitely very efficient and friendly too.”
“My new house had a tankless water heater without a descaling filter. Tried to call multiple places around but I did not get many responses back. Efficient Water Heaters had prompt and great communication, and I was able to book an appointment right away. Installation was done very quickly and professionally by Martin. I could not be happier!”
Reviews shown in customers' own words. We do not publish star ratings or aggregate ratings on this page.
Where we work
Navien Tankless Service Areas
Searching for Navien tankless water heater service near you? We serve 21 cities across the South Bay and Peninsula from San Jose. Open your city for local details, then request an estimate.
San Jose + Santa Clara County
San Mateo County / Peninsula
South Santa Clara County
Browse all Navien tankless service areas →
Same-day Navien service across San Jose and the South Bay.
Call (408) 470-0191Free phone estimate
Get a Navien Phone Estimate
Send a photo of your data plate for a faster estimate. A specialist — not a call center — reviews every request.
Answers
Navien Tankless FAQs — San Jose, CA
Yes — Efficient Water Heaters, Inc. is a certified Navien Service Specialist repairing Navien tankless units across San Jose daily, with same-day service available. We diagnose error codes, ignition and flow faults, and scale-related failures, then repair with correct Navien parts. Licensed CSLB #1008381, open 24 hours a day, 7 days a week.
Navien Problem? Get Hot Water Back Today.
Certified Navien Service Specialist · Same-day service · Open 24/7
Licensed CSLB #1008381 · Bonded & Insured · Navien Service Specialist · Serving San Jose since 1997