Baxi E119 fault code: low system pressure and how to clear it
Baxi E119 means system water pressure has dropped too low. How to repressurise to 1 to 1.5 bar with a built-in, external, or Easy-Fill loop, and when it means a leak.
What this means
Baxi assigns E119 to low water pressure in the heating system, below the level the boiler needs to operate. It is cleared by repressurising to between 1 and 1.5 bar with the filling device fitted to the boiler, and it points to a leak only if the pressure will not stay up afterwards.
Equipment and model context
Baxi and Potterton domestic boilers that display E119
- Baxi 600
- Baxi 800
- Baxi Platinum
- Potterton boilers sharing the E119 code
This covers Baxi and Potterton boilers whose published fault guidance lists E119. Baxi uses E118 for a related low-pressure condition on some models, so match the exact digits, and confirm the boiler model before choosing a filling method.
What you may notice
- The Baxi display shows E119 and central heating and hot water stop working.
- The pressure gauge reads below about half a bar with the system cold.
Likely causes
- Water has left the sealed system through radiator bleeding, a small leak at a valve, joint, or radiator, or a discharge from the pressure relief pipe outside.
- A waterlogged expansion vessel, one that has lost the air behind its diaphragm, holds the cold reading down and lets it sag further between cycles.
Diagnostic paths
E119 clears after one repressurise and stays clear
The gauge was low, one fill to 1.5 bar with the boiler filling device brought it back, and the pressure has held through a day or more of normal heating since.
Treat it as a single loss. Record the date and the pressure you filled to, and glance at the gauge weekly. Nothing further is needed while it holds in the normal band.
E119 comes back and the pressure keeps sinking
The gauge falls below half a bar again within days of each fill, or there are damp marks near pipework or a drip from the outside overflow pipe.
Stop refilling and arrange a Gas Safe registered engineer to find where water is leaving. Note the refill dates and amounts so the rate of loss can guide the search.
E119 is the control acting on a low pressure reading. Raising the reading means adding water through whichever filling device the boiler has, then isolating it again.
- Mains cold supplyHigher pressure water available to top up the system
- Filling deviceBuilt-in loop, external hose, or Easy-Fill lever
- Sealed heating circuitPipes and radiators held at about 1 to 1.5 bar cold
- Pressure sensorReports system pressure to the boiler control
- Control boardShows E119 and stops the boiler below the limit
| Filling device on the boiler | How it is operated | After filling |
|---|---|---|
| Built-in filling loop | Two handles under the boiler, both turned to open | Turn both handles fully back to closed |
| External braided hose loop | Two valves with a flexible hose between them, both opened | Close both valves; a detachable hose is then removed |
| Easy-Fill lever | A single lever pushed or pulled to admit water | Return the lever to its rest position once in band |
Repressurising is the owner step, and the method depends on the boiler
Baxi treats E119 as something a homeowner can correct. With the boiler switched off, check the gauge and, if it is low, admit water until it reads between 1 and 1.5 bar with the system cold. The device varies by model: a built-in loop has two handles under the boiler, an external loop has two valves joined by a braided hose, and some models use an Easy-Fill lever. In every case the device is opened only long enough to bring the gauge into band and then closed fully.
Filling to the middle of the band rather than the top leaves room for the pressure to rise as the water heats without lifting the relief valve. Once the gauge is in band, the boiler is switched back on and the code clears if a shortage was the whole problem. Overfilling past 1.5 bar cold is worth avoiding, because it can push the hot pressure into the red and start a discharge from the outside pipe.
One refill is fine, a pattern of refills is not
A sealed system should hold its pressure for long stretches once it is set. A single drop can come from bleeding a radiator or from a system that was slightly under-filled at the last service. If the pressure holds after one top-up, that is the end of it. If E119 returns, the refill has told you that water is leaving the system, and each further top-up adds fresh oxygenated water that speeds internal corrosion.
Tracing the loss is engineer work. It can be an external weep at a radiator valve, a leak under a floor, a discharge from a failed expansion vessel through the relief valve, or an internal fault. The rate matters: a drop over weeks and a drop over hours send an engineer to different places, so keep a simple log of when you refilled and by how much.
What to give the technician
Give the engineer the Baxi or Potterton model, the gauge reading before and after topping up, how many times you have refilled in the last month, whether any radiator work was done, and whether the outside overflow pipe has dripped.
Safe homeowner checks
- With the boiler off, read the gauge and, if it is low, admit water with the boiler filling device until it reads 1 to 1.5 bar cold, then close the device fully.
- Keep a short note of each repressurise, the date, and the pressure before and after, so a repeat loss can be measured.
Is a reset appropriate?
The boiler should clear E119 on its own once the pressure is back in band. Do not keep repressurising when it will not hold, because repeated refilling introduces oxygen into the system.
When to call a technician
- A pressure that will not hold, visible damp or staining, a dripping outside overflow pipe, or any expansion vessel or internal check needs a Gas Safe registered engineer.
Questions people ask about this
What is the difference between Baxi E118 and E119?
Both sit in the low-pressure family. Some Baxi models show E118 and others E119 for a pressure that has dropped below the operating level. Match the exact digits on the display before topping up.
How do I repressurise a Baxi boiler with E119?
Switch the boiler off, open the filling device fitted to your model, watch the gauge rise to 1 to 1.5 bar cold, then close the device fully. The code should clear once the pressure is in band.
Why does Baxi E119 keep coming back?
Something is letting water out, or the expansion vessel is flat so the reading sinks each time the boiler cools. Either way a Gas Safe engineer is needed, and topping up again just puts more oxygen into the water.
Evidence recordHow this page was checked
official manufacturer support article · checked 2026-09-09
Every technical claim above was written from primary documentation held in the HVAC Bench evidence record: Baxi technical literature. Where a source limits a definition to certain models, test conditions, or product classes, that limit is repeated here rather than generalised.
- Documentation class
- official manufacturer support article
- Scope of the definition
- Baxi and Potterton domestic boilers that display E119
- Last checked
- 2026-09-09