Navien Control Board Replacement — What This Part Does
The control board (PCB or main board) is the brain of your Navien tankless water heater. It reads sensor inputs, manages ignition and gas valve operation, controls the pump and flow, monitors temperatures, and displays error codes. It also handles communication between all the components to keep hot water flowing safely.
The board fails from power surges, moisture intrusion, overheating caused by heat exchanger scale or blocked venting, loose or corroded wiring connections, and age-related solder joint failure. A board fault often shows up as an E015 (abnormal control board) or E016 (communication error or overheating) code, but many other symptoms can point back to a bad PCB once you rule out sensors, wiring, and overheating problems.
Signs It Needs Replacing
- Error code E015 or E016 displayed The unit shows E015 for abnormal control board or E016 for communication error or heat exchanger overheating, depending on your model.
- Unit powers on but won’t ignite The display lights up and the fan runs, but the burner never fires even when you open a hot tap.
- Blank or scrambled display The screen stays dark, flickers randomly, or shows garbled characters even after a full power cycle.
- Intermittent shutdowns or lockouts The heater starts normally, then shuts off mid-cycle with no consistent error code or repeats lockouts for no clear reason.
- No response to any input Pressing buttons or opening hot taps produces no change, no sound, and no display activity.
- Persistent fault after clearing other causes You’ve verified power, checked all wiring connectors, confirmed the emergency switch is closed, and ruled out sensor or overheating problems, but the fault returns.
How to Replace It
- Turn off electrical power to the water heater at the circuit breaker, then turn off the gas supply valve and close the cold-water inlet valve.
- Remove the front cover by unscrewing the bottom screws and lifting the panel free.
- Take a clear photo of all wire connections to the control board so you have a wiring reference during reassembly.
- Disconnect every wire harness and connector from the board by gently pulling straight out or releasing any locking tabs.
- Remove the mounting screws securing the control board to the chassis, then slide or lift the board free.
- Position the new control board in the same location, align the mounting holes, and fasten it with the original screws.
- Reconnect each wire harness to the matching connector on the new board, using your reference photo to confirm correct placement.
- Reinstall the front cover, open the cold-water inlet valve, and turn on the gas supply.
- Restore electrical power at the breaker, watch the display initialize, and verify the unit completes a normal startup cycle without error codes.
The Part You Need
| Part | Notes |
|---|---|
| Navien control board / main PCB | Amazon | Board part numbers are model-specific. Find your exact model and serial number on the data plate (typically inside the front cover or on the right side of the unit), then reference the Navien parts diagram or contact a Navien distributor to confirm the correct board number for your model and revision. |
When to Call a Pro
If you are not comfortable working with 120 V or 240 V electrical connections, or if your diagnosis is uncertain (many board symptoms are actually caused by bad sensors, wiring faults, or heat exchanger overheating), call a licensed plumber or Navien-certified technician. Any work involving gas lines, burner assembly access, or advanced diagnostics with a multimeter should be performed by a professional. If the new board still throws the same error code, the root cause may be elsewhere in the system and professional diagnosis is required. For gas line, burner, or igniter work, or if you ever smell gas, stop and call a licensed technician.