What the E119 code means
E119 is the low pressure code on older Potterton ranges, including the Promax, Titanium and Gold Combi HE. Their manuals describe it as "water pressure switch not operated", and the Gold Combi HE guide adds that it is displayed when the primary water pressure is less than 0.5 bar. The pressure switch must close before the boiler is allowed to light, so with too little water in the system it simply stays off.
If you have a newer Potterton Assure, you will not see E119. The Assure reports low pressure as code 118, described as "primary system water pressure too low". The cause and the fix are the same, and our page on Baxi E118 covers that code in detail, as Assure and current Baxi boilers share the same controls.
On Promax, Titanium and Gold displays, E119 appears as "E1" alternating with "19", because the screen shows two characters at a time.
Common causes of E119
Pressure lost after bleeding radiators
Every radiator you bleed lets out a little pressure. Doing several in one go is one of the most common reasons for E119.
Slow natural loss
Sealed systems lose small amounts of pressure over months. On an older Promax or Titanium that has not been checked for a while, this may be the whole story.
Leaks around the house
Radiator valves, towel rails and joints under floors can weep slowly. Look for damp patches, stains and crusty deposits.
Expansion vessel and relief valve
On these older boilers, an expansion vessel that has lost its charge is a common cause of repeated E119. The pressure rises too high when hot, the relief valve lets water out, and the pressure ends up low once the system cools.
Faulty pressure switch
If the gauge shows a healthy pressure but E119 stays, the switch itself or its wiring may have failed.
| Cause | Typical sign | Who fixes it |
|---|---|---|
| Radiators recently bled | Pressure dropped straight afterwards | You, via the filling loop |
| Slow natural loss | Gauge low, no other symptoms | You, via the filling loop |
| Leak on pipes or radiators | Damp or staining, pressure keeps falling | Plumber or Gas Safe engineer |
| Expansion vessel or relief valve | Very high when hot, drips from the outside pipe | Gas Safe engineer |
| Faulty pressure switch | Gauge normal but E119 remains | Gas Safe engineer |
Safe checks you can do yourself
- Turn the heating off and let the system cool. Read the pressure gauge on the front of the boiler.
- If it is below 1 bar, find the filling loop. On most Promax and Titanium installations this is a braided hose with a valve at each end, fitted under the boiler.
- Open the valves slowly and watch the gauge. Close them once it reaches 1 to 1.5 bar.
- Check both valves are fully closed so the pressure does not keep rising.
- If E119 does not clear by itself, turn the selector switch to the reset position and hold it for about five seconds. Try no more than two or three times.
- Check radiators, visible pipes and the area under the boiler for signs of water, and look at the copper pipe outside for drips.
- Note the pressure each day for a week.
Our step-by-step guide on how to repressurise a boiler covers the filling loop in more detail.
Older Potterton manuals give a normal operating range of 1 to 2.5 bar when the system is running. Filling to 1 to 1.5 bar when cold leaves room for the pressure to rise as it heats. If it climbs close to 3 bar, see our guide to boiler pressure that is too high.
When to call a Gas Safe engineer
If you are topping up more than once every few weeks, something is losing water. Call a Gas Safe registered engineer if the pressure keeps dropping, if water drips from the relief pipe outside, if there is water under the boiler, or if the gauge reads normal but E119 will not clear. The expansion vessel, relief valve and pressure switch are inside the boiler and must not be touched by a homeowner. For a leak at the boiler itself, our guide to a boiler leaking water explains what to do next.
When you book, tell the engineer how quickly the pressure falls and whether you have noticed it climbing high when the heating is on. A system that swings from very high when hot to low when cold usually needs the expansion vessel recharging, which is often a quick job.
Do not remove the casing to look for a leak or check the pressure switch. Water near live electrical parts and gas components is a job for a qualified engineer.
Typical repair costs in the UK
Typical ranges only, which vary by area and access.
| Job | Typical UK cost |
|---|---|
| Topping up yourself | Free |
| Engineer call-out and diagnosis | Typically £80 to £150 |
| Expansion vessel recharge | Typically £80 to £150 |
| Pressure switch replacement | Typically £100 to £200 |
| Pressure relief valve replacement | Typically £120 to £220 |
How to stop E119 coming back
Check the gauge monthly and top up after bleeding radiators. Fix small drips early. Promax, Titanium and Gold boilers are now getting on in years, so an annual service matters more than ever. It lets the engineer recharge the expansion vessel and check the relief valve before either causes repeat pressure loss. See our boiler service cost guide for what to expect. The same fault on Baxi Duo-tec and Platinum boilers is covered on our Baxi E119 page.