Navien error code 353 indicates an abnormal water pressure sensor reading, which you can often resolve with a simple system power reset or by checking for sensor moisture.
Table of Contents
- What does the Navien error code 353 mean?
- What usually causes the Navien 353 error code?
- How can you perform quick fixes for this error?
- What next steps should you take if resets fail?
- Quick reference table
- When should you call a technician for this error?
- What should you have ready before calling support?
- How can you prevent the Navien 353 error?
What does the Navien error code 353 mean?
Navien error code 353 indicates an abnormal operation or voltage reading from the internal water pressure sensor within the system boiler.
This fault typically triggers when the boiler’s control board detects an irregular voltage signal from the pressure sensor, falling outside the normal operating range. It often relates to sensor moisture, wiring faults, or trapped system air depending on your exact model lineup.
- The digital display shows error 353 when sensor voltage is abnormal.
- Voltage readings falling outside the normal operating range trigger immediate system shutdown.
- This code specifically targets water pressure monitoring circuits inside system boilers.
- It protects internal components from running under improper pressure conditions.
- Behavior may slightly differ across various Navien model generations.
What usually causes the Navien 353 error code?
The error is commonly caused by moisture on the pressure sensor, loose wiring connections, a faulty sensor component, or trapped air.
Condensation or minor internal leaks can easily wet the pressure sensor and corrupt its electrical signals. Alternatively, physical blockages, trapped air pockets within the heat exchanger, or a failing sensor component itself will frequently trigger this protective system shutdown.
- Moisture or condensation accumulation on the pressure sensor body.
- Loose electrical wiring connections between the sensor and circuit board.
- Trapped air pockets circulating inside the primary heat exchanger loops.
- A physically damaged or failed internal water pressure sensor.
- A malfunctioning main control board supplying incorrect reference voltage.
How can you perform quick fixes for this error?
You can safely attempt a simple power reset and check your system water pressure levels before moving to advanced troubleshooting.
Always ensure safety by turning off electrical power to the unit before inspecting any external components. Simple power cycling can clear temporary glitches in the digital control board and restore normal communication with the water pressure sensor quickly.
- Locate the electrical power switch and shut down the system completely.
- Wait approximately five full minutes to drain residual electrical charge.
- Turn the power switch back on to initiate a fresh system reboot.
- Press the back or reset button on the front control panel.
- Check the digital display screen to see if the error code clears.
What next steps should you take if resets fail?
Inspect the internal wiring harness connections to the sensor and check for any visible signs of water leakage or condensation.
If a standard power cycle fails to clear the code, a deeper inspection of the internal components is required. Turn off the main electrical breaker to protect against electrical shock before opening the front cabinet panel to check for moisture.
- Safely disconnect power to the unit before opening the metal cabinet.
- Inspect the wiring harness plugged into the water pressure sensor.
- Ensure all electrical pin connectors are clean and firmly attached.
- Look closely around the sensor assembly for any signs of water leaks.
- Consult your user manual to verify specific wiring layout diagrams.
Quick reference table
Use this quick reference table to match specific physical symptoms with their most likely causes and recommended repair actions.
Troubleshooting complex heating equipment requires carefully matching observed behavioral symptoms to known technical failure points. Reviewing these common indicators helps determine whether a simple adjustment will suffice or if professional intervention is required for your equipment.
| Symptom | Likely cause / fix |
|---|---|
| Error 353 appears after rebooting | Sensor fault; replace pressure sensor component. |
| Code returns during heavy heating | Trapped air; bleed system loops thoroughly. |
| Sensor wiring looks wet or corroded | Moisture leak; dry area and fix leak source. |
| Display flickers alongside error code | Power issue; check control board voltage output. |
When should you call a technician for this error?
You should immediately stop troubleshooting and call a professional if you notice gas leaks, electrical burning smells, or persistent internal leaks.
Gas appliances and complex heating systems carry serious safety risks if handled incorrectly by untrained homeowners. Attempting component-level repairs without proper technical certification can void your manufacturer warranty or create severe safety hazards in your home living environment.
- Stop immediately if you smell or suspect any natural gas leaks.
- Call a licensed professional when dealing with internal electrical component replacements.
- Do not attempt repairs if water is actively leaking onto electrical parts.
- Contact certified technicians if standard resets fail to clear the error.
- Avoid opening sealed gas valve compartments under any circumstances.
What should you have ready before calling support?
Gather your exact boiler model number, serial number, warranty details, and a clear history of the troubleshooting steps you attempted.
Having this information ready allows technical support or a licensed service technician to diagnose the issue much faster. Locate the rating plate on the side of your boiler cabinet to find your specific unit identification numbers before placing the call.
- Write down your exact Navien boiler model and serial numbers.
- Locate your original purchase receipt or current warranty documentation.
- Make a detailed list of every troubleshooting step you already tried.
- Note the exact time and conditions when the error code appears.
- Keep the manufacturer customer service phone number handy for quick access.
How can you prevent the Navien 353 error?
Regular annual professional maintenance and keeping system water pressure within the recommended range will prevent this error from recurring.
Routine annual service checks help catch minor leaks, pressure fluctuations, and component wear before they cause critical system faults. Maintaining proper operating habits ensures your Navien combi boiler runs efficiently throughout the entire heating season without unexpected breakdowns.
- Schedule professional annual maintenance checks before every winter heating season.
- Monitor your system water pressure gauges regularly to catch fluctuations early.
- Bleed trapped air from your radiators and piping networks promptly.
- Keep the area around your boiler clean and free from moisture.
- Address minor plumbing leaks immediately before they damage electronic sensors.
Frequently Asked Questions
Does error code 353 mean my Navien boiler is about to leak?
Error code 353 primarily points to an abnormal electrical signal from the water pressure sensor rather than an active flood. However, minor internal condensation or seepage can sometimes cause the sensor wiring to get wet. You should inspect the immediate area around the sensor for any slow drips.
Why does error code 353 keep coming back after a manual reset?
If the error returns immediately after a reset, it usually indicates a persistent hardware failure or continuous moisture exposure. The pressure sensor itself may have failed electrically, or a wiring harness connection might be loose. At this point, professional diagnostic testing is necessary.
Can I use my hot water while error code 353 is displayed?
Most Navien system and combi boilers will initiate a complete safety shutdown when code 353 triggers to prevent internal damage. Because the unit locks out operation, you typically will not have access to central heating or domestic hot water until the fault is cleared.
Does this error code affect different Navien models in the same way?
While code 353 generally relates to the water pressure sensor across most NCB and system boiler lines, specific diagnostic steps can vary. Always cross-reference your specific user manual version because older and newer generations may feature different internal component layouts.
Is it safe to open the boiler cabinet to check the sensor?
You can safely remove the outer cabinet panel only after turning off the main electrical breaker to prevent shock hazards. Never touch internal gas valves or electrical terminals if you lack professional training, and always call a technician if you feel unsure.
Bottom Line
The single best action to take right now is to perform a complete power reset by turning off the breaker for five minutes. If the Navien error code 353 persists after powering back on, inspect the sensor wiring for moisture or contact a licensed technician.
Sources
- Navien Service Manual
- Navien Technical Support
- Manufacturer Support Page
- HVAC Technical Database