Navien Error Code E352: APS Sensor Abnormality
Warning: Your Navien boiler has detected an issue with the Aquastat Pressure Switch (APS) sensor, which could lead to system malfunction. It's safe to use, but needs professional attention.
How to Fix Navien Code E352
- Check your boiler's pressure gauge. If it's above 30 PSI, you may have excess pressure in the system.
- If the pressure is too high, you can bleed the system's air using the bleed valve, but be careful not to lose too much water.
- If the pressure is normal, or if bleeding the system doesn't resolve the issue, contact a professional HVAC technician
How to Reset Navien Code E352
- 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 E352 Mean?
The E352 error on your Navien boiler indicates an abnormality with the Aquastat Pressure Switch (APS) sensor. This sensor is responsible for monitoring the water pressure in your heating system. When it detects an issue, it sends an error signal to the boiler's control board, displaying the E352 code. While your boiler is still operational, it's important to have this issue addressed by a professional to prevent potential system damage or reduced efficiency.
Common Causes
- A faulty Aquastat Pressure Switch (APS) sensor
- Incorrect water pressure in the system
- Air or other non-compressible substances in the system
- Wiring issues between the APS sensor and the boiler's control board
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Boiler is displaying the E352 error | Measure the water pressure using the pressure gauge on your boiler | Between 12-30 PSI |
| Pressure is above 30 PSI | Bleed the system using the bleed valve | Pressure to drop to a safe level (12-30 PSI) |
| Pressure is normal but E352 persists | Inspect the wiring between the APS sensor and the boiler's control board for any damage or disconnections | Wiring to be intact and properly connected |
Applicable Navien Models
Source Documentation
Referenced in 5 official Navien technical manuals.
| Manual | Page | Reason | Action |
|---|---|---|---|
| NFB-H Installation & Operation Manual | 116 | High Water Pressure | Check water pressure. |
| Navien NCB-H Installation & Operation Manual | 129 | High Water Pressure | Contact technical support at 1-800-519-8794. |
| Navien NFB-H Installation & Operation Manual | 116 | High Water Pressure | Check water pressure. |
| Navien NFC-H Installation & Operation Manual | 127 | High water pressure | Auto RESET |
| Navien NHB-H Installation & Operation Manual | 119 | High Water Pressure | Check water pressure. |
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Aquastat Pressure Switch (APS) Sensor | Navien 9010140000 | — | Find Part |
Related Codes on Same Models
Other codes that affect the same Navien model families as E352.
| Code | Description | Severity |
|---|---|---|
| E001 | Ignition Failure | Warning |
| E003 | Abnormal Ignition | Warning |
| E004 | False Flame Detection | Warning |
| E031 | Inlet Thermistor Open/Short | Warning |
| E046 | Outlet Thermistor Open/Short | Warning |
| E110 | Exhaust Blocked | Warning |
| E205 | Water Flow Sensor Failure | Warning |
| E517 | Water Flow Switch Failure | Warning |
| E736 | CH Return Thermistor Failure | Warning |
| E740 | CH Buffer Tank Thermistor | Warning |