Navien E593
Navien E593: front panel key fault
Short answer
Navien E593 means abnormal operation of a front panel key: one of the buttons on the display panel is stuck, pressed for too long or not reading correctly. Moisture, dirt or damage to the panel can cause it. Navien's manual says to contact technical support, and a faulty panel is replaced.
In this guide
The front panel is how you set the temperature, read codes and reset the heater. E593 means the control board thinks a button is misbehaving.
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.
What you can check
- Make sure nothing is leaning against or pressing on the panel.
- Look for moisture or condensation on the panel. Navien notes the front panel is moisture resistant but not waterproof.
- Gently clean the panel surface with a dry or slightly damp cloth.
- Press the Back button to reset.
If it keeps coming back
A technician checks the panel and its connection to the control board. A failed front panel is replaced. Water dripping onto the heater from above should be fixed at the same time.
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 water cause Navien E593?
Yes. The panel resists moisture but is not waterproof, so drips or condensation can cause button faults.
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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 |