Low water pressure, occurs when the pressure drops below Mini- mal_Pressure, or when the pres- sure drops below 4.5 psi
The Low Water Pressure Sensor error code on Dunkirk boilers indicates low water pressure, occurs when the pressure drops below mini- mal_pressure, or when the pres- sure drops below 4.5 psi.
Dunkirk Low Water Pressure Sensor means: low water pressure, occurs when the pressure drops below mini- mal_pressure, or when the pres- sure drops below 4.5 psi. On this component the documented failure modes are not enough water pres- sure or system water pressure too low, or a leak somewhere in the system. You can safely reset the boiler once — if Low Water Pressure Sensor returns, do not keep resetting. A qualified heating engineer should diagnose the root cause.
What Does Low Water Pressure Sensor Mean
The Low Water Pressure Sensor code is shown by the boiler’s control board when it detects low water pressure, occurs when the pressure drops below mini- mal_pressure, or when the pres- sure drops below 4.5 psi. The boiler then stops instead of continuing to run in that condition: the code is the appliance reporting a problem, not proof that the boiler is broken.
| What you see on the boiler |
|---|
| The display shows Low Water Pressure Sensor and the boiler stops until the fault is cleared |
Common Causes
The first cause below is the one the Dunkirk service literature publishes for this code (source: dunkirk.com). The others are the failure modes documented for the same component on other boilers, confirmed by 7 different manufacturers.
| Cause |
|---|
| not enough water pres- sure |
| System water pressure too low, or a leak somewhere in the system |
Safety Warning
Low Water Pressure Sensor involves electrical or pressure-related components. Do not attempt repairs without proper qualifications. Ensure the boiler is electrically isolated before any inspection. If you notice water leaks, unusual sounds, or pressure anomalies, contact a qualified heating engineer immediately.
Parts & Prices
Prices shown are indicative. Actual prices and availability vary by region.
How to Fix It
Repressurise the system to the pressure stated on the boiler — typically 1.0–1.5 bar (15–22 psi) when cold. If it drops again, look for a leak on pipework, radiator valves and the pressure relief discharge.
Refer to the Dunkirk service documentation for the detailed procedure. Only a qualified engineer should carry out these repairs.
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Affected Models
Dunkirk models that can display fault code Low Water Pressure Sensor:
| Model Family | Output Range | Frequency |
|---|---|---|
| All Dunkirk models | — | Possible |
Frequently Asked Questions
Repressurise the system to the pressure stated on the boiler — typically 1.0–1.5 bar (15–22 psi) when cold. If it drops again, look for a leak on pipework, radiator valves and the pressure relief discharge. According to the technical documentation, this is the first check on the list for Low Water Pressure Sensor.
Low Water Pressure Sensor is not classified as a high-severity fault, so the boiler can be reset once. If Low Water Pressure Sensor comes back, stop resetting: the underlying cause is still there and needs a qualified heating engineer.