Navien E515
Navien E515: control board fault
Short answer
E515 means abnormal operation of the PCB, the heater's main circuit board. Navien's manual tells owners to make sure the electrical cord is properly grounded. If grounding and power are fine and the code persists, the control board usually needs to be replaced.
In this guide
The printed circuit board (PCB) is the heater's brain. E515 means the board has detected a fault in its own operation.
The meaning below comes from Navien's manuals for its NPE condensing tankless water heaters. Many codes are shared with Navien combi boilers, but check the manual for your model if something does not match.
What to check first
- Make sure the heater is plugged into a properly grounded outlet. This is the step Navien's user manual gives for E515.
- Avoid extension cords and adapters that can drop the ground connection.
- Think about whether the code started after a storm, power surge or outage. Surges can damage control boards.
- Look for water dripping onto the unit, which can damage electronics.
How to reset a Navien
- Close all hot water taps.
- Press the power button on the front panel to turn the unit off, wait about a minute, then turn it back on.
- Open a hot tap and watch whether the code returns.
If the board needs replacing
A new control board is one of the more expensive repair parts on a tankless heater. A technician should confirm the board is really at fault, not a shorted sensor or component, before replacing it. After a replacement, the new board may need its settings configured for your installation.
Protect the new board
A surge protector rated for appliances, a properly grounded outlet and keeping the unit dry all help prevent a repeat.
See every code on our Navien error codes page.
Common questions
Is Navien E515 covered by warranty?
It depends on the age of the unit and whether it was registered. Check your warranty terms before paying for a new board.
Can a power surge cause Navien E515?
Surges can damage control boards. If E515 started after a storm or outage, mention it to your technician.
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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 |