Boiler
E119
The E119 error code on a Baxi boiler indicates that the system water pressure has dropped too low for safe operation. It’s one of the most common Baxi faults — and often one homeowners can fix themselves in minutes.
What does this error mean?
Your Baxi boiler continuously monitors internal water pressure via a pressure sensor. E119 triggers when that pressure falls below approximately 0.5 bar, which is too low for the boiler to fire safely. The boiler locks out to protect the heat exchanger from running dry and overheating. Normal operating pressure for most Baxi boilers is 1–1.5 bar when cold.
Est. repair cost
£0 if resolved by re-pressurising; £80–£200 for professional repair of PRV, expansion vessel, or leak
🔍 Likely causes
🛠️ Step-by-step fix
Check the pressure gauge on the boiler’s front panel. If it reads below 1 bar (or the needle is in the red/low zone), low pressure is confirmed — proceed to re-pressurise.
Locate the filling loop — usually a braided silver hose or blue-handled valve underneath the boiler connecting two pipes. If you cannot find it, check your Baxi manual or look for a label on the boiler casing.
Slowly open the filling loop valve(s) and watch the pressure gauge rise. Stop when it reaches 1.2–1.5 bar. Do not exceed 2 bar. Close the valve(s) firmly.
Press the reset button on the boiler (usually marked with a flame or restart symbol) and hold for 3 seconds. The boiler should restart and the E119 code should clear.
Inspect all visible radiators, pipework, and the area beneath the boiler for any signs of drips or damp patches. If you find a leak, do not re-pressurise — call a heating engineer.
If the pressure drops again within days or weeks, do not keep topping up. This points to an underlying fault — a leaking PRV, expansion vessel failure, or a hidden leak — and requires a professional diagnosis.
📞 When to call a professional
Call a Gas Safe registered engineer if you cannot locate the filling loop, if the boiler pressure drops repeatedly after topping up, or if you find any evidence of a water leak. Tell the engineer you have a Baxi E119 fault, that pressure has been dropping, and roughly how often you’ve needed to top it up — this helps them diagnose quickly whether it’s a PRV, expansion vessel, or leak issue.
⚖️ Repair or replace?
A Gas Safe engineer call-out to diagnose and fix the underlying cause of recurring E119 typically costs £80–£200 depending on the fault — a PRV replacement or expansion vessel recharge sits at the lower end, while tracking and repairing a hidden leak can be higher. If your Baxi boiler is over 10–12 years old and requiring repeated pressure top-ups alongside other faults, replacement may be more cost-effective than ongoing repairs. A new Baxi boiler costs £1,500–£2,500 fully installed — use the 50% rule: if repairs exceed half the cost of a new boiler, replace it.