Baxi E119 Fault Code: Low System Pressure
If your Baxi boiler is showing E119, it has detected that the water pressure in your heating system has dropped too low. Here is what that means and the safe, homeowner-friendly way to put it right.
Quick answer
The Baxi E119 fault code means low water (system) pressure: the boiler has detected that the pressure in your sealed heating circuit has dropped below the minimum it needs to run, so it locks out rather than firing.
Check the gauge — a healthy system sits at roughly 1 to 1.5 bar when cold, and below 1 bar is the usual trigger. Topping the system back up via the filling loop to 1–1.5 bar is a homeowner-safe job that normally clears the code.
If the pressure keeps dropping every few days, book a Gas Safe registered engineer, as that points to a leak, expansion vessel or pressure relief valve fault.
What the Baxi E119 fault code means
On a Baxi boiler, the E119 fault code indicates low water (system) pressure. Your central heating is a sealed, pressurised circuit, and the boiler constantly monitors that pressure using a sensor.
When the reading falls below the minimum the boiler needs to run safely, it locks out and displays E119 rather than continuing to fire. It is one of the most common Baxi fault codes — and, reassuringly, one of the few that you can often resolve yourself.
You will usually find that the heating and hot water stop working, the pressure gauge on the front of the boiler is reading below 1 bar, and the display is showing E119. The good news is that low pressure is a symptom rather than damage in itself, so topping the system back up will normally clear the code.
Quick check: Look at the pressure gauge on your boiler. A healthy combi or system boiler sits at roughly 1 to 1.5 bar when cold, rising to around 2 bar when the heating is hot. If the needle is below 1 bar, low pressure is almost certainly behind your E119.
Why does the pressure drop?
A small, gradual loss of pressure over many months is normal as tiny amounts of air work out of the system. A noticeable or repeated drop usually points to one of the following:
- Recently bled radiators — releasing trapped air lowers the system pressure, so the gauge often drops after a bleed.
- A small leak somewhere in the pipework, on a radiator valve, or at a joint.
- A failing expansion vessel, which can no longer absorb the expansion of heated water.
- A weeping or faulty pressure relief valve (PRV), which may be letting water escape through the external discharge pipe.
If you have to repressurise once and the boiler then behaves for months, there is little to worry about. If the pressure keeps dropping every few days, something needs investigating by an engineer.
How to repressurise a Baxi boiler safely
Topping up the pressure via the filling loop is a homeowner-safe job — it involves the water side of the system only, not the gas. Work slowly and keep an eye on the gauge.
- Turn the boiler off and let it cool. It is easier and safer to set the pressure on a cold system.
- Locate the filling loop. This is usually a silver braided hose with a valve (or two) underneath the boiler, connecting the cold mains to the heating pipework. Some Baxi models have a built-in keyed filling valve instead.
- Open the valve(s) slowly. You should hear water flowing into the system. Watch the pressure gauge begin to climb.
- Stop at 1 to 1.5 bar. Close the valve(s) firmly as soon as the needle reaches this range. Do not let it climb past 1.5 bar cold.
- Reset the boiler. Most Baxi models clear the lockout automatically once pressure is restored; if not, use the reset button on the front panel once. The E119 code should disappear and the boiler should fire up.
- Return the filling loop to its normal state — close it fully, and on some models disconnect the hose as the manufacturer advises.
Do not over-pressurise. If you go too high, the boiler may release water through the pressure relief valve and you will be back where you started.
If you accidentally over-fill, the safe DIY fix is to bleed a small amount of water from a radiator (using a bleed key and a cloth) to bring the gauge back down. Never touch the gas valve, the flue, the casing or the sealed combustion components — those are Gas Safe work only.
When to call a Gas Safe registered engineer
Repressurising once is fine. But you should book a Gas Safe registered engineer if any of the following apply:
- The pressure keeps dropping and you are repressurising every few days — this points to a leak, a faulty expansion vessel or a failing PRV.
- You can see water dripping from the boiler, from pipe joints, or from the external discharge pipe outside the wall.
- The E119 code returns immediately or the boiler will not refill at all.
- You are not confident locating or operating the filling loop.
Diagnosing and replacing an expansion vessel, pressure relief valve or a hidden leak is not a DIY job — it involves the sealed pressurised circuit and the boiler's internals, so it must be done by a registered engineer. You can check any engineer's credentials on the Gas Safe Register.
If you ever smell gas, leave the property and call the national gas emergency line on 0800 111 999.
Where boiler cover comes in
A persistent E119 caused by a faulty expansion vessel or a leaking PRV can mean a callout charge plus parts.
A boiler cover or central heating policy can spread that cost into a fixed monthly payment, with parts and labour included, and an annual service that often catches a tired expansion vessel before it fails.
If you are weighing it up, our guide on whether boiler cover is worth it walks through the maths, and what boiler cover actually includes explains the typical exclusions to watch for.
For the specifics of low pressure itself — and how to stop it recurring — see our companion guide on what to do when your boiler pressure is too low.
| Pressure reading | What it means | What to do |
|---|---|---|
| Below 1 bar (cold) | Low — likely cause of E119 | Repressurise via the filling loop |
| 1–1.5 bar (cold) | Normal cold pressure | No action needed |
| Around 2 bar (hot) | Normal when heating is running | No action needed |
| Dropping repeatedly | Possible leak, vessel or PRV fault | Book a Gas Safe engineer |
Is the Baxi E119 fault code dangerous?
No, E119 is a protective lockout rather than a sign of immediate danger. The boiler stops firing because there is too little water pressure to run safely. Restoring the pressure usually clears it. If you smell gas, that is a separate emergency — call 0800 111 999.
What pressure should my Baxi boiler be at?
Around 1 to 1.5 bar when the system is cold, rising to roughly 2 bar when the heating is hot. Below 1 bar cold is considered low and is the usual trigger for E119.
Why does my Baxi keep showing E119 after I repressurise it?
If the pressure won't hold, there is likely a leak, a failing expansion vessel or a faulty pressure relief valve. These are not DIY repairs — book a Gas Safe registered engineer to find and fix the cause.
Can I repressurise the boiler myself?
Yes. Topping up via the filling loop is a homeowner-safe task involving the water side only. Just bring the gauge to 1–1.5 bar cold and avoid over-pressurising. Anything involving the gas valve, flue, casing or internal components must be left to a registered engineer.
Does boiler cover include low-pressure faults?
Many policies cover repairs to the parts behind recurring low pressure, such as the expansion vessel and PRV, plus an annual service. Cover levels vary, so check the policy terms. You can compare what different providers include below.
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