Navien Error Code E762: Dual Venturi Failure
Warning: This error locks out your Navien boiler/water heater, but there's no immediate gas or CO danger; call a professional to inspect the dual venturi system.
How to Fix Navien Code E762
- Step 1: Turn off the unit at the power switch and gas shut-off valve to ensure safety.
- Step 2: Check the air intake filter and area around the venturi for visible dust or blockage; clean if safe to reach (do not disassemble).
- Step 3: Reset the unit by turning power off for 30 seconds, then back on. If code returns, call a Navien-certified technician.
How to Reset Navien Code E762
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs repair.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Navien Error Code E762 Mean?
The E762 code on your Navien unit indicates a dual venturi failure. The venturi is a part that mixes air and gas for proper combustion—on newer Navien models (like the NPF or NCB-E), there are two venturis, one for each burner stage. When the control board detects a mismatch or abnormal pressure signal from the venturi assembly, it triggers this lockout. This usually means the venturi is clogged with debris, has a faulty gasket, or the O-ring is damaged. In rare cases, the issue is a bad pressure switch or wiring. The unit won't fire until the problem is fixed.
Common Causes
- Clogged or dirty venturi due to dusty installation or poor air quality
- Damaged O-ring or gasket on the dual venturi assembly causing an air leak
- Faulty pressure switch (DPS) not reading correct differential pressure
- Loose or corroded wiring between the venturi sensor and main board
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Unit shows E762 and burner does not fire | Measure voltage across the dual venturi pressure switch (DPS) terminals | 0 VAC when venturi is not activated; 120 VAC when operating (if applicable) |
| Unit fires briefly then locks out with E762 | Check combustion fan RPM and compare to rated speed (e.g., 3000 RPM) | RPM should match within 5% of manufacturer spec for the given stage |
| Unit has history of gas odor or soot | Inspect venturi O-rings and gasket for cracks or flattening | O-rings should be round, pliable, and seated flush; no soot or carbon buildup |
Applicable Navien Models
Source Documentation
Referenced in 6 official Navien technical manuals.
| Manual | Page | Reason | Action |
|---|---|---|---|
| NFB-H Installation & Operation Manual | 116 | Vent Pipe Not Fully Inserted | Insert pipe 3 inches into exhaust collar. |
| Navien NCB-H Installation & Operation Manual | 130 | Vent Pipe Not Fully Inserted | Contact technical support at 1-800-519-8794. |
| Navien NFB-H Installation & Operation Manual | 116 | Vent Pipe Not Fully Inserted | Insert pipe 3 inches into exhaust collar. |
| Navien NFC-H Installation & Operation Manual | 128 | Abnormal flue gas duct: Vent pipe not properly inserted | Auto RESET |
| Navien NHB-H Installation & Operation Manual | 119 | Vent Pipe Not Fully Inserted | Insert pipe 2-3“/4 (70 mm) into exhaust collar. |
| Navien NPF Installation & Operation Manual | 128 | Improper vent pipe installation | This error occurs when the vent pipes are not installed properly. ● Check if the vent pipes are installed properly on the furnace. ● If this error occurs continuously, contact Technical Support at 1-800-519-8794. |
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Dual Venturi Assembly | 30017153A | — | Find Part |
| Venturi O-Ring Kit | 30017154A | — | Find Part |
| Differential Pressure Switch (DPS) | 30017155A | — | Find Part |
Related Codes on Same Models
Other codes that affect the same Navien model families as E762.
| Code | Description | Severity |
|---|---|---|
| E001 | Ignition Failure | Warning |
| E003 | Abnormal Ignition | Warning |
| E004 | False Flame Detection | Warning |
| E031 | Inlet Thermistor Open/Short | Warning |
| E046 | Outlet Thermistor Open/Short | Warning |
| E110 | Exhaust Blocked | Warning |
| E205 | Water Flow Sensor Failure | Warning |
| E517 | Water Flow Switch Failure | Warning |
| E736 | CH Return Thermistor Failure | Warning |
| E740 | CH Buffer Tank Thermistor | Warning |