An E119 error on a Baxi or Potterton boiler is most often encountered in practice as a low water pressure lockout, and topping the system back up usually clears it. Before you do anything, check the pressure gauge: it should sit between 1 and 1.5 bar with the heating off.

There is a second cause worth knowing about, and almost nobody mentions it. We cover both below, along with what Baxi itself actually publishes.

How to fix an E119: repressurising your boiler

1. Find the filling loop. Usually a silver braided hose beneath the boiler with a tap or lever at each end, or an internal key-operated filler on newer Baxi appliances.
2. Open both valves slowly. You will hear water entering the system.
3. Watch the gauge. Close the valves as soon as it reaches 1.5 bar. Do not overfill.
4. Close both valves fully and check the loop is not left open.
5. Reset the boiler and let it fire.

If the pressure holds, that is the job done. If it drops again within a week or two you have a leak somewhere in the system, and finding that leak matters considerably more than topping the pressure up again.

What Baxi actually publishes, and why it says E118

This is the part other pages leave out. Baxi’s own published error-code list does not contain E119. The code Baxi publishes for low water pressure is E118, “Water pressure LOW (<0.5 bar)”.

So if your display reads E118 rather than E119, you are looking at Baxi’s documented low-pressure code, and the repressurising steps above are exactly right for it.

If your display reads E119, the low-pressure route is still the sensible first check, because that is overwhelmingly what E119 turns out to be in practice on the appliances that show it. But we are not going to state it as a Baxi-published fact, because it is not one. That distinction matters when there is a second cause in play.

The second cause: a frozen condensate pipe

Baxi’s own customer guidance lists E119 among the codes that can appear when a condensate pipe has frozen, alongside E23, E53, E133 and E128.

Your boiler produces acidic water as it condenses, and that drains away through a plastic pipe, usually to an outside drain. In cold weather that pipe can freeze, the water backs up, and the boiler locks out. It is the single most common winter callout in the trade and it is very often fixable without an engineer.

• Is your pressure gauge healthy? If pressure is between 1 and 1.5 bar and you still have E119, pressure is not your problem.
• Is it cold outside? Frozen condensate is a hard-frost fault.
• Find the pipe. A plastic pipe, usually 22mm or 32mm, running from the boiler through the wall to a drain or soakaway.
• Thaw it gently. Warm, not boiling, water poured slowly along the exposed length, or a hot water bottle held against it. Never use a naked flame and never use boiling water.
• Reset the boiler once the pipe has cleared.

When E119 needs an engineer

Call someone if:

• The pressure will not hold, or drops again within days, that is a leak
• You cannot find a filling loop, or you are not confident using one
• The condensate pipe is clear and the pressure is fine, but the code persists
• The boiler locks out repeatedly after repressurising
• You can see water anywhere around the boiler or on pipework

Getting it sorted

Vantage Plumbing & Heating is Gas Safe registered and works across Hertfordshire and Bedfordshire. If your Baxi or Potterton has locked out and the simple checks have not cleared it, we can find out why rather than keep topping it up.

Frequently asked questions

What does E119 mean on a Baxi boiler?

In practice E119 is most commonly a low water pressure lockout, and repressurising to between 1 and 1.5 bar usually clears it. Worth knowing: Baxi’s own published error-code list does not contain E119, and the code Baxi publishes for low water pressure is E118, “Water pressure LOW (<0.5 bar)”. Baxi’s customer guidance also lists E119 among codes that can appear when a condensate pipe has frozen, so check both.

What is the difference between E118 and E119?

E118 is the code Baxi publishes for low water pressure, defined as below 0.5 bar. E119 is not in Baxi’s published list but appears on certain Baxi and Potterton appliances and is generally handled the same way. The fix for both starts with checking the pressure gauge and repressurising if it reads low.

Is E119 the same as the E119 fault code on a Potterton?

Yes. Baxi and Potterton share a parent company and share fault codes across a number of appliances, so E119 behaves the same way on both.

Why does my Baxi keep showing E119?

A pressure drop that keeps recurring means water is leaving the system somewhere. That is a leak, and it needs finding rather than repeatedly topping up. If the pressure is healthy and the code still shows, check the condensate pipe, particularly in cold weather.

Can I fix an E119 myself?

Usually yes. Repressurising through the filling loop and thawing a frozen condensate pipe are both householder jobs. If the pressure will not hold, if you cannot find the filling loop, or if the code persists once both are ruled out, call a Gas Safe registered engineer.

Is an E119 error dangerous?

When to call an engineer

Worked through the checks and it is still locking out? That is the point to stop and get it looked at properly. Call 01462 506374 and speak to someone who fits boilers for a living. Gas Safe 956889, covering Hertfordshire, Bedfordshire and Cambridgeshire, with a fixed price agreed up front.

Where to next

• Boiler installation and repair
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