The short answer
E119 on a Baxi means the heating system water pressure has dropped too low for the boiler to run safely. Check the pressure gauge. If it reads under 1 bar, top the system up to between 1 and 1.5 bar using the filling loop, then reset the boiler. If the pressure keeps falling within days, there is a leak, a passing pressure relief valve or a flat expansion vessel. If the gauge reads normally but E119 stays, the pressure sensor has probably failed. London repair costs run from £90 to £330.
What the law requires
- What does E119 mean on a Baxi?
- How to tell what is going on in one minute
- How to top up a Baxi and clear E119
- Why does the pressure keep dropping?
- What an engineer does on an E119 call
- How much does an E119 repair cost in London?
- Is E119 dangerous?
- How to stop E119 coming back
- Baxi E119, quick answers
What does E119 mean on a Baxi?
E119 is the low water pressure code on Baxi boilers, including the Platinum, Duo-tec and similar combi ranges. The boiler has a pressure sensor in the heating circuit. When the reading falls below its minimum, the boiler stops firing and shows E119, because running a boiler with too little water in the system can overheat the heat exchanger.
On most Baxi models the fault clears once the pressure is restored and the boiler is reset. That makes E119 one of the friendlier codes. Often the fix takes five minutes and costs nothing.
How to tell what is going on in one minute
Look at the pressure gauge on the front of the boiler, with the boiler cold.
- Under 1 bar: the system has lost water. Top it up using the steps below.
- Between 1 and 2 bar but E119 still shows: the pressure sensor or its wiring has probably failed. This needs an engineer.
- Rising to 2.5 or 3 bar when hot, then near zero when cold: the expansion vessel has lost its charge. Topping up will make this worse. Book an engineer.
How to top up a Baxi and clear E119
This is safe to do yourself and needs no tools. The boiler case stays closed.
Switch the boiler off and let it cool.
Find the filling loop. On most Baxi combis it is a short flexible hose with a tap at each end, or a filling key, under the boiler.
Open the loop slowly and watch the gauge climb.
Stop between 1 and 1.5 bar. Do not go above 1.5 bar cold. Water expands as it heats, and a system filled to 2 bar cold can reach nearly 3 bar hot, which lifts the pressure relief valve.
Close both taps firmly. If your loop is a removable hose, disconnect it at one end afterwards.
Reset the boiler. Turn the selector to the reset position, hold it for about five seconds, then release.
Bleed any radiators that are cold at the top, then check the gauge again, because bleeding releases water and lowers the pressure.
If the pressure holds for a month, it was ordinary loss. If it is back to E119 within a week, read on.
Why does the pressure keep dropping?
A leak. Radiator valves, pipe joints, a corroded radiator or a weep at the boiler. Pressure that falls from 1.5 bar to E119 within days means water is going somewhere. Damp patches, stained ceilings and warm patches on floors are the usual signs.
A passing pressure relief valve. The valve dumps water outside if pressure rises too high. Once its seat wears, it dribbles. Look for a drip from the small copper pipe that exits the wall near the boiler.
A flat expansion vessel. When its air charge leaks away, the pressure spikes when the system heats, the relief valve lifts and dumps water, and the pressure then falls to nothing when it cools. Every top-up makes the next dump worse.
Recent radiator bleeding. Bleeding several radiators can drop the pressure by half a bar or more. This is normal.
A failed pressure sensor. The gauge reads fine but the boiler believes the pressure is low.
Half the house cold? Describe which radiators and where they are cold, and we will usually name the fix on the phone.
What an engineer does on an E119 call
First the pressure is set correctly and watched through the visit to see whether it holds. Then the expansion vessel charge is checked at its valve with a tyre gauge, the relief valve and visible pipework are inspected, and the system is pressure-tested. If a leak is suspected under floors, dye, thermal imaging or sectional pressure testing finds it without lifting boards at random. If everything holds, the sensor is tested against a reference gauge.
How much does an E119 repair cost in London?
Fixed price quoted after diagnosis.
- Top-up, system check and radiator bleed: £90 to £130.
- Pressure sensor replacement: £110 to £210 fitted.
- Filling loop replacement: £80 to £150.
- Pressure relief valve replacement: £130 to £230 fitted.
- Expansion vessel recharge: £90 to £150.
- Expansion vessel replacement: £190 to £330 fitted.
- Leak location and repair: £120 to £400, depending on where it is.
If the boiler is over twelve years old and the repair is major, ask for a replacement quote alongside it. Our repair or replace guide explains the half-cost rule.
Is E119 dangerous?
No. The boiler stopped itself before any harm could happen. The things to avoid are topping up above 1.5 bar cold, running the boiler for weeks while topping up just enough to clear the fault, and opening the boiler casing. If you smell gas, leave the property and call the National Gas Emergency line on 0800 111 999.
How to stop E119 coming back
Glance at the gauge once a month through winter. Ask for the expansion vessel to be checked at every annual service. If the relief valve has been replaced, have the vessel checked in the same visit. And fit a magnetic filter if you do not have one, because sludge corrodes radiators from the inside, which is where many slow leaks start.
Baxi E119, quick answers
My Baxi shows E119, what do I do?
Check the gauge. If it is under 1 bar, top up to between 1 and 1.5 bar and reset. If it returns within a week, book an engineer.
What pressure should a Baxi have?
Between 1 and 1.5 bar cold, rising to about 2 bar when hot.
The gauge reads 1.5 bar but E119 will not clear. Why?
The pressure sensor or its wiring has failed. It needs an engineer.
Can I keep using the boiler with E119?
It will not fire while the fault is active. Top up and it runs.
Is E119 the same as the Ideal F1 or Vaillant F22?
They are the equivalent low pressure codes on other makes. Our guides on Ideal F1 and Vaillant F22 cover those.