E119 means low system water pressure on Baxi, Potterton and Main alike — the three brands share a control platform, so the code, the threshold (about 0.5 bar) and the fix are identical. Re-pressurise to 1–1.5 bar using the filling loop with the heating off, then reset. Topping up more than a couple of times a year means something is losing water — a weeping radiator valve, a leak, or a flat expansion vessel dumping through the pressure-relief pipe.
The brand is printed on the front casing. Tap your brand for the full causes, fixes and repair costs.
| Brand | What E119 means | Severity | DIY? |
|---|---|---|---|
B Baxi | The E119 fault code indicates that your boiler's system pressure has dropped below 0.5 bar, which is too low for safe and efficient operation. Full guide → | Lockout — engineer likely | Some checks |
M Main | The E119 fault code indicates that your Main boiler has detected water pressure that has dropped too low to operate safely — typically at or below 0.5 bar. Full guide → | Lockout — engineer likely | Some checks |
P Potterton | The E119 code appears on Potterton boilers when the system water pressure has dropped too low — typically below 0.5 bar — for the boiler to operate safely. Full guide → | Lockout — engineer likely | Some checks |
The E119 fault code indicates that your boiler's system pressure has dropped below 0.5 bar, which is too low for safe and efficient operation. Baxi boilers are designed to shut themselves down automatically when this happens, preventing damage to internal components such as the pump and heat exchanger. Until the pressure is restored to the correct level, the boiler will remain locked out and produce no heating or hot water.
The E119 fault code indicates that your Main boiler has detected water pressure that has dropped too low to operate safely — typically at or below 0.5 bar. Once the internal pressure sensor registers this, the boiler locks out and displays E119 as a protective measure. Note that pressing the reset button will not clear this fault; the pressure must be restored first. On some displays, the code appears as 'E1' followed by '19'.
The E119 code appears on Potterton boilers when the system water pressure has dropped too low — typically below 0.5 bar — for the boiler to operate safely. Once the pressure sensor detects this shortfall, the boiler locks out and displays E119 to prevent damage to internal components. You may also see this displayed as E-119, E1 19, or similar spacing variations; they all refer to the same fault. Normal operating pressure for most Potterton systems should sit between 1.0 and 1.5 bar when cold.
Causes, fixes & costs for Potterton E119 → · All Potterton codes
Broadly, yes — on Baxi, Main and Potterton the E119 code points to the same class of fault, and the recommended response is similar. Model-specific details such as sub-codes and reset procedures still vary, so follow the page for your own brand.
On some brands there are safe homeowner checks first — typically system pressure, the condensate pipe in cold weather, and a single reset. Where the code is a simple pressure or reset condition, that may be all it needs. Never open the boiler casing yourself.
For gas boilers, a Gas Safe registered engineer — it is a legal requirement for any work on the appliance. If you smell gas at any point, leave the property and call the National Gas Emergency line on 0800 111 999.
General guidance only — not a substitute for professional advice, and not certified by a registered engineer. Any work on a gas appliance must be carried out by a Gas Safe registered engineer. If you smell gas, call 0800 111 999.
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