Navien Error E778: Flow Sensor Fault
The flow sensor is reading abnormally or has failed. We diagnose and repair it across Greater Vancouver — same-day and after-hours.
The flow sensor is reading abnormally or has failed.
Navien fault codes can vary by model and series. Use this as a guide — the same code can have more than one cause. Our Technical Safety BC–licensed technicians read the code, confirm it against your unit's manual, and diagnose the true cause before any repair.
Likely causes of Navien error E778
- Scaled or failed flow sensor
- Debris
- Wiring fault
What you can safely check
- Note no/low hot water on demand
Beyond these checks, do not open the unit or touch gas/electrical parts — BC law requires a licensed gas fitter. Call us for a proper diagnosis.
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For your safety and to keep your manufacturer warranty valid, BoilerPart.ca does not sell loose boiler parts over the counter or for self-installation. Under BC regulations, gas appliance components must be installed by a licensed gas fitter. Every part we source is genuine OEM and is professionally fitted, tested, and certified by our Technical Safety BC–licensed technicians as part of a complete repair or installation.
Parts often behind Navien error E778
Genuine Navien parts we supply and professionally install — never for DIY.
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Every repair and installation is backed by genuine parts, licensed workmanship, and a promise to make it right.
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Every repair and installation is backed by our written workmanship guarantee. If a part we installed fails because of our work, we make it right.
Genuine OEM Parts
We fit only manufacturer-original (OEM) components so your boiler performs to spec and keeps its factory warranty intact.
Manufacturer Warranty Honoured
As an authorised service provider for the brands we work on, our installs preserve and register your manufacturer parts warranty.
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All work is completed by Technical Safety BC–licensed gas fitters. We are fully licensed, bonded and insured for your protection.
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Backed by the full HVAC resources of CanroHeat.ca and four decades of service in Greater Vancouver since 1985.
Navien Error E778 Repair Across Metro Vancouver
Frequently Asked Questions
Fix Navien Error E778 Today
Licensed Navien diagnosis and repair with genuine parts — same-day and after-hours across Greater Vancouver.
A Division of CanroHeat.ca · Licensed Gas Fitters · Serving Greater Vancouver since 1985