Navien Error Code E593: Abnormal Panel Key
How to Fix Navien Code E593
- Step 1: Inspect the control panel for any visible signs of damage, moisture, or debris. Clean the panel gently with a dry cloth.
- Step 2: Try pressing each button on the control panel individually to see if any feel stuck or unresponsive. Sometimes, repeatedly pressing a button can dislodge it if it's slightly stuck.
- Step 3: If the error persists after cleaning and checking the buttons, contact a qualified HVAC technician to diagnose and repair the unit.
How to Reset Navien Code E593
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs repair.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Navien Error Code E593 Mean?
The E593 error code on your Navien tankless water heater or combi-boiler indicates an abnormal panel key input. Basically, the unit's control board is receiving unexpected or incorrect signals from the buttons on the front panel. This could be due to a stuck button, a short in the wiring, or a problem with the control board itself. When this happens, the unit shuts down as a safety measure to prevent unintended operation or damage. You'll likely notice a lack of hot water or heating, depending on your Navien model. This error is important because it prevents the unit from operating correctly and could potentially lead to further issues if left unaddressed. While some causes are minor, others can point to a more significant electrical problem within the unit. It's best to troubleshoot this issue to get your Navien back up and running reliably.
Common Causes
- Stuck or continuously pressed button on the front control panel.
- Moisture or debris interfering with the control panel buttons or circuitry.
- Loose or damaged wiring connecting the control panel to the main control board.
- Faulty front control panel.
- Defective main control board.
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Unit displays E593 error | Disconnect the front control panel ribbon cable from the main control board. Clear the error. Does the error return? | Error clears, indicating a problem with the front panel or its wiring. |
| Error clears after disconnecting the front panel | Check the ribbon cable for continuity and shorts using a multimeter. | Each wire should have continuity, and there should be no shorts between wires. |
| Ribbon cable is good, and the error persists with the front panel connected | Measure the voltage at the main control board where the front panel connects. Refer to the Navien service manual for the correct pinout and expected voltage levels when buttons are pressed. | Voltage changes should correspond to button presses as per the service manual. |
| All wiring and front panel tests pass | Inspect the main control board for any signs of damage, such as burnt components or corrosion. | The main control board should appear physically sound with no visible damage. |
Applicable Navien Models
Source Documentation
Referenced in 1 official Navien technical manual.
| Manual | Page | Reason | Action |
|---|---|---|---|
| Navien NPF Installation & Operation Manual | 127 | Abnormal Panel Key | This error occurs when the buttons on the front control panel do not operate properly. ● If this error occurs continuously, contact Technical Support at 1-800-519-8794. |
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Front Control Panel | — | — | — |
| Main Control Board | 30010647A | — | Find Part |
| Ribbon Cable | — | — | — |
Related Codes on Same Models
Other codes that affect the same Navien model families as E593.
| Code | Description | Severity |
|---|---|---|
| E001 | Ignition Failure | Warning |
| E003 | Abnormal Ignition | Warning |
| E004 | False Flame Detection | Warning |
| E012 | Flame Loss | Warning |
| E016 | Overheating | Warning |
| E030 | Exhaust Overheat Sensor | Warning |
| E031 | Inlet Thermistor Open/Short | Warning |
| E046 | Outlet Thermistor Open/Short | Warning |
| E047 | DHW Thermistor Open/Short | Warning |
| E060 | Fan Motor Abnormality | Warning |