E788 🟡 Repair Required
Navien Error Code E788: Pump Failure
⚠️ Your Navien boiler has detected a pump failure, which may cause system lockout and no heat.
How to Fix Navien Code E788
- Check your boiler's water level and top it off if necessary, but be careful not to overfill
- Listen for unusual noises from the pump, which could indicate a mechanical failure
- If the boiler is still under warranty, contact Navien's customer support for assistance
What Does Navien Error Code E788 Mean?
The E788 error on your Navien boiler indicates a failure in the circulation pump. This pump is responsible for circulating hot water through your heating system. When it fails, your boiler won't be able to distribute heat, leading to a system lockout. This is a yellow hazard level because while it's not an immediate safety risk, it does require professional repair to restore heat.
Common Causes of Navien Code E788
- Worn out pump motor or bearings
- Clogged pump due to debris or air in the system
- Faulty pump control board or wiring
- Low water levels or air in the system causing pump cavitation
Applicable Navien Models
Source Documentation
This error code is documented in 6 official Navien technical manuals.
NFB-H Installation & Operation ManualPage 116
ReasonIncorrect Gas Type Setting
ActionCheck DIP switch setting.
Navien NFC-H Installation & Operation ManualPage 128
ReasonAbnormal Gas Setting
ActionManual RESET (Start-up Wizard )
Navien NCB-H Installation & Operation ManualPage 130
ReasonIncorrect Gas Type Setting
ActionCheck the supplied gas type and match the gas type setting on the PCB DIP switch.
Navien NFB-H Installation & Operation ManualPage 116
ReasonIncorrect Gas Type Setting
ActionCheck DIP switch setting.
Navien NHB-H Installation & Operation ManualPage 119
ReasonIncorrect Gas Type Setting
ActionCheck DIP switch setting.
Navien NPF Installation & Operation ManualPage 128
ReasonAbnormal gas type settings
ActionThis error occurs when the DIP switches are not set properly. ● Check if the DIP switch settings for the furnace’s gas type are set properly.
Need a Pro to Fix Navien Code E788?
A licensed HVAC technician can diagnose and fix this issue quickly.
Find a Licensed Tech Near You →Replacement Parts for Navien Tankless Water Heater Code E788
Circulation Pump OEM: N100000010
Pump Control Board OEM: N100000011