Navien E782
Navien E782: main panel communication fault
Short answer
Navien E782 means abnormal operation of main panel communication: the control board and the front display panel are not communicating. Loose or damaged panel wiring, moisture or a failed panel or board are typical causes. Navien's manual says to contact technical support.
In this guide
The front panel and the control board exchange information constantly. E782 means that conversation has stopped working properly.
The meaning and recommended action below come from Navien's User's Information Manual for NPE-2 condensing water heaters (NPE-180A2, NPE-210A2, NPE-240A2 and the S2 models). Navien technical support: 1-800-519-8794.
Common causes
- A loose connector between the panel and the control board, sometimes after service
- Moisture on the panel or its wiring
- A failed front panel or control board
- Electrical disturbance from a power surge
What to do
- Press the Back button to reset, or turn the unit off and on with the power button.
- If it returns, call your installer or Navien technical support.
If the code appeared right after the heater was serviced, ask the technician to check the panel connection first.
Before you call
Have the model number and serial number from the rating plate on the side of the unit ready, along with the date it was installed and the exact code. Navien asks for this information when you contact technical support, and your installer should be your first call for warranty service.
See every code on our Navien error codes page.
Common questions
Can I still get hot water with Navien E782?
It depends on whether the heater can still operate, but you lose control and code display, so have it fixed promptly.
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Other Navien codes
| Code | Meaning |
|---|---|
| E003 | Ignition failure |
| E004 | False flame detection |
| E012 | Flame loss |
| E016 | Heat exchanger overheat |
| E030 | Abnormal exhaust temperature |
| E031 | Burner overheating |
| E046 | Limit control (high limit switch) abnormal |
| E047 | Exhaust temperature sensor (thermistor) open or short |
| E060 | Dual venturi abnormal operation |
| E109 | Fan motor abnormal operation |
| E110 | Exhaust blockage (condensate blockage) |
| E407 | Hot water outlet temperature sensor open or short |
| E421 | Cold water inlet temperature sensor open or short |
| E432 | Cold water inlet 2 sensor open or short |
| E434 | Water adjustment valve fault |
| E438 | Circulation pump fault |
| E439 | Flow sensor fault |
| E441 | Second hot water temperature sensor open or short |
| E445 | Bypass mixing valve fault |
| E515 | Control board (PCB) abnormal operation |
| E517 | DIP switch setting fault |
| E593 | Front panel key fault |
| E594 | EEPROM (memory) fault |
| E615 | Input and memory fault |
| E736 | Cascade communication fault |
| E740 | Outdoor temperature sensor fault |
| E760 | Flushing or service alarm |
| E762 | Vent pipe not properly inserted |
| E773 | Using the wrong gas |
| E782 | Main panel communication fault |
| E785 | Flow switch or flow sensor fault (with AHU) |
| E788 | Gas type mismatch between board DIP switch and front panel |