Navien Error Code 351: Causes & Repair in Indianapolis
Navien Error Code 351 indicates the unit has detected abnormal water pressure within the system. This error may be caused by excessive water pressure, pressure fluctuations, faulty sensors, plumbing restrictions, scale buildup, or issues with pressure control devices.
If your Navien tankless water heater is displaying Error Code 351, Hot Water Pros can quickly diagnose the cause and restore reliable hot water service throughout Indianapolis and surrounding communities.
QUICK ANSWER
What Navien Error Code 351 Means
Error 351 means the control board is reading abnormal water pressure in the system. The heater may shut down until the pressure problem is corrected.
Top 3 causes
High water pressure or a failing pressure reducing valve (PRV)
A waterlogged expansion tank or pressure swings
Scale, a dirty inlet filter or a restricted water line
When to call a pro
If 351 keeps coming back, schedule Navien tankless water heater repair. We can test your home's water pressure and check the PRV and expansion tank. Our Carefree tankless plan includes annual service.
BEFORE YOU CALL
Safe Things To Check First
Supply valve: Make sure the cold-water valve to the heater is fully open.
Recent changes: Think back to recent plumbing work or water softener changes, and look for visible leaks.
Timing: Note when the code shows up, such as overnight or during heavy use. It helps us find the cause faster.
One reset: Reset the unit once. If 351 comes back, call.
Leave it to a pro: adjusting the pressure reducing valve or expansion tank, and anything inside the unit.
Water dripping from the relief valve? See Navien leaking water. Still showing 351? Call 317-922-9043 or book online.
What Does Navien Error Code 351 Mean?
Navien Error Code 351 indicates the control board has detected water pressure readings outside the unit's normal operating range. To protect internal components and ensure safe operation, the system may shut down until the underlying pressure issue is corrected.
Common Causes of Navien Error Code 351
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High water pressure
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Failing pressure reducing valve (PRV)
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Water pressure fluctuations
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Expansion tank problems
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Scale buildup inside the heat exchanger
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Dirty inlet filter
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Restricted water flow
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Faulty pressure sensor
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Plumbing restrictions
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Control board communication issues
High water pressure is one of the most common causes of Navien Error Code 351. A failing pressure reducing valve (PRV), waterlogged expansion tank, or pressure fluctuations can cause the unit to shut down and display this error code.
If your Navien is repeatedly showing Error 351, Hot Water Pros can test your home's water pressure, inspect your PRV and expansion tank, and diagnose the root cause of the problem.
Call Today: 317-922-9043
Serving Indianapolis, Carmel, Fishers, Westfield, Noblesville, Greenwood, Brownsburg, Whitestown, and Zionsville.
Can I Fix Navien Error Code 351 Myself?
Homeowners can safely check:
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Recent plumbing work
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Water shutoff valves
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Water softener bypass settings
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Visible leaks
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Obvious pressure problems at fixtures
However, diagnosing Error Code 351 often requires pressure testing, inspection of the PRV, evaluation of expansion tank performance, and examination of internal tankless components.
Signs You Need Professional Navien Repair
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Repeated Error 351 shutdowns
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Water pressure fluctuations
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Unusually high pressure at fixtures
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Relief valve discharge
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Inconsistent hot water
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Tankless system resets
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No hot water production
Why Indianapolis Homeowners Choose Hot Water Pros
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Licensed Indiana plumbing contractor
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Experienced with Navien tankless systems
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Same-day service available
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Water pressure diagnostics
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Tankless flushing and maintenance
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Upfront pricing
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Serving Indianapolis, Carmel, Fishers, Westfield, Noblesville, Greenwood, Brownsburg, Whitestown, and Zionsville
We Repair All Major Navien Models
Our technicians service all major Navien tankless water heater models including:
• Navien NPE-240A2
• Navien NPE-210A2
• Navien NPE-180A2
• Navien NPE-S2 Series
• Navien NCB Series
• Navien NHB Series
Navien NPE-240A2
199,000 BTU
Navien NPE-210S2
180,000 BTU
Navien NPE-240S2
199,000 BTU
Navien NPE-180A2
150,000 BTU
Navien Error Code 351 Repair FAQs
What is Navien Error Code 351?
Navien Error Code 351 indicates abnormal water pressure has been detected within the system.
Can high water pressure cause Error 351?
Yes. Excessive incoming water pressure is one of the most common causes.
Can a bad PRV cause Error 351?
Yes. A failing pressure reducing valve can allow unsafe pressure levels and trigger the code.
Can scale buildup cause Error 351?
Yes. Mineral buildup may affect flow characteristics and contribute to pressure-related issues.
How much does it cost to fix Navien Error Code 351?
Repair costs depend on the cause. We provide upfront pricing before any work begins, and warranty coverage is available on qualifying repairs.
Do you repair Navien Error Code 351 in Indianapolis?
Yes. Hot Water Pros provides Navien Error Code 351 diagnosis and repair throughout Indianapolis and surrounding communities, with same-day service available. Call or text 317-922-9043 to schedule.
Locally Owned & Operated
Hot Water Pros proudly provides Navien Error Code 351 repair throughout Indianapolis, Carmel, Fishers, Westfield, Noblesville, Greenwood, Brownsburg, Whitestown, Cicero, and Zionsville. Our Navien trained technicians can quickly diagnose water pressure problems and restore reliable hot water to your home.
TANKLESS WATER HEATER SERVICES
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From installation to maintenance and repairs, we handle all your tankless water heater needs with honest pricing, expert workmanship, and the best brands in the industry.
Professional installation of tankless water heaters for maximum performance and efficiency.
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Fast diagnostics and expert repairs to keep your tankless water heater running like new.
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