Baxi E119 Fault Code
The E119 fault means system water pressure has dropped below the minimum operating threshold. It is the most homeowner-resolvable Baxi fault — but only once you have confirmed there is no visible leak.
What is the Baxi E119 fault code?
The Baxi E119 fault is triggered when the pressure sensor detects the central heating system has fallen below the minimum threshold — typically 0.5 bar on 600, 800, and Platinum+ models. The boiler locks out to prevent running dry and damaging the heat exchanger. In most cases, repressurising via the filling loop and resetting clears E119 immediately. If pressure drops again within weeks, a leak or failed expansion vessel is present.
What causes the E119 fault?
All sealed systems lose a small amount of pressure over time. A drop of up to 0.2 bar per year is normal. Below 0.5 bar the boiler locks out with E119.
A dripping radiator valve, weeping pipe joint, or leaking pump gland allows water to escape. Pressure dropping more than 0.5 bar within a few weeks of repressurising points to a leak.
The vessel air charge depletes over years. A failed vessel causes pressure to drop dramatically on cooling — often falling below the E119 threshold overnight.
Bleeding radiators releases water alongside air, reducing system pressure. Always top up after any bleed.
A stuck-open automatic air vent slowly allows water to escape the system.
If both filling loop valves are not fully closed after repressurising, the loop can slowly drain back and let pressure fall.
What you can safely check yourself
Find the pressure gauge on the boiler front panel. Cold system pressure should be 1.0–1.5 bar. Below 0.8 bar: repressurise. At zero: check for visible leaks before filling.
Locate the filling loop — typically a braided hose with two valves beneath or beside the boiler. Open both valves slowly until the gauge reads 1.2–1.5 bar. Close both valves fully. If you cannot identify the filling loop, call an engineer.
Hold the reset button for 3 seconds. Watch the gauge over the next 48 hours. If it drops more than 0.3 bar within a week, there is a leak — call an engineer.
Do not reset the boiler more than once if the fault code returns immediately. Repeated resets without diagnosis can mask a worsening fault.
What needs a Gas Safe engineer
- Pressure test the system to locate any hidden leak in pipework, radiators, or fittings
- Inspect the expansion vessel — recharge with nitrogen if pressure is low, replace if membrane has failed
- Check automatic air vents and replace if weeping
- Inspect pump gland seals for dripping
- Check radiator valve gland nuts for slow leaks
- Replace filling loop or isolating valves if internal leakage is confirmed
Expansion vessel failures are common across South London. Thames Water's hard water accelerates corrosion of the rubber diaphragm inside the vessel. In Wandsworth, Merton, Lewisham, Lambeth, Southwark, Greenwich, and Bromley, Baxi Platinum+ and 600 series boilers over 10 years old frequently develop expansion vessel faults alongside the E119 code. Reion checks expansion vessel charge pressure on every annual service.
How much does a E119 repair cost?
Costs below are UK averages. Reion provides a fixed quote after the £80 diagnostic visit — no obligation to proceed.
How to reset a Baxi boiler showing E119
Repressurise to 1.2 bar via the filling loop before resetting.
Ensure both filling loop valves are fully closed after repressurising.
Hold the reset button for 3 seconds.
Monitor the pressure gauge — it should remain stable as the system heats.
If pressure drops again within days, call a Gas Safe engineer to locate the leak.
E119 alone is very rarely a reason to consider boiler replacement. The exception is if a pressure test reveals a cracked heat exchanger as the source of pressure loss.
Common questions about the Baxi E119 fault
Can I fix a Baxi E119 fault myself?
Why does my Baxi boiler keep showing E119?
What is the correct pressure for a Baxi boiler?
How much does a Baxi E119 repair cost in London?
How do I know if my Baxi needs a new expansion vessel?
Other Baxi fault codes
Need a Baxi engineer in London?
Reion is Gas Safe registered (919881), based in South London, and available 24/7. Fixed price after the diagnostic visit — no hidden charges.
