L2 is not a pressure code
Ideal's fault-code list defines a flashing L and 2 as flame loss or ignition lockout. The boiler asked for a flame, the flame either never arrived or went out during the cycle, and the appliance shut itself down rather than keep opening a gas valve into a chamber with nothing burning in it. That is a safety response working correctly.
It has nothing to do with the water in your heating system. The Ideal code for low water pressure is F1, and if the system were short of water that is what you would be looking at. We write about leaks for a living, and this page exists mainly to tell you that this one is almost certainly not ours.
The four checks Ideal ask you to make
Ideal's own guidance for L2 is short, and it is worth doing before anyone charges you for a visit.
- Reset the boiler. Once. A single failed ignition attempt on a cold morning is common and often does not repeat.
- Check there is credit on the gas meter if yours is a prepayment meter. This is the most frequent cause of a lockout that looks catastrophic and is not.
- Check whether other gas appliances are working. A hob that will not light too means the problem is the supply, not the boiler.
- Check the yellow gas isolation valve under the boiler. It is a quarter-turn lever, and it gets knocked closed more often than you would expect in a cupboard used for storage.
Ideal also flag a specific sound. If the boiler gurgles or gargles while it tries to fire, there is a blockage, and you should contact your installer rather than keep resetting.
The winter cause, and the one thing worth checking yourself
In cold weather the condensate pipe is the usual suspect behind L2. Every condensing boiler produces acidic waste water and drains it through a narrow plastic pipe. Where that pipe runs outside or through an unheated garage it can freeze, the condensate backs up into the boiler, and the appliance locks out. Ideal's guidance during winter is explicit that a blocked condensate pipe should be checked when L2 appears.
Thawing one is a job you can do, with two conditions. Use warm water, never boiling, because boiling water on a cold plastic pipe splits it. And only attempt a pipe you can reach standing safely on the ground. A condensate pipe at height is a ladder job, and it is not worth a fall.
Do not keep resetting it
Ideal's list includes L5, which appears when the boiler has been reset too many times within fifteen minutes. Repeated resetting does not fix an ignition fault. It clears the record of it, sends unburnt gas into the chamber on each failed attempt, and eventually locks the appliance out of your reach as well. Two attempts is the sensible limit before you pick up the phone.
The narrow overlap where a leak is involved
There is a version of this where water is the cause, and it is the reason we mention L2 at all.
A leak above or inside the boiler can drip onto the ignition electrode, the flame sensing probe or the control board. Water on an electrode stops it generating the spark, or stops the board seeing a flame that is actually there, and the boiler responds with a flame loss lockout. The pattern to look for is an L2 that comes and goes with no relation to the weather, on a boiler whose case interior is damp, sometimes with corrosion staining on the tray beneath.
The other pattern worth knowing: L2 alternating with F1. That combination is a system losing water badly enough to affect both the pressure sensor and the burn, and the leak is the root of it. In that case the sequence matters. The leak is found and repaired first, then a Gas Safe engineer checks the boiler, because there is no point commissioning an appliance on a circuit that is still emptying itself.
If your Ideal is also dropping pressure, start with the F1 fault code rather than this page.
Who to call, honestly
For a plain L2 with a healthy pressure gauge, call a Gas Safe registered engineer. Anything inside the boiler case, anything touching the gas valve, the electrode, the fan or the flue, is gas work and must be done by someone on the register. Ideal's own instruction when their troubleshooting steps do not clear a code is to contact them or a qualified engineer quoting the code. That is the right route, and it is not us.
Call us when the water is the problem rather than the flame:
- Water is dripping into or pooling inside the boiler case and you do not know where it is coming from.
- The pressure gauge falls between lockouts and you are topping the system up to keep it running.
- There is a damp patch, a warm spot underfoot or a ceiling stain somewhere on the heating circuit.
- The outside discharge pipe from the relief valve drips whenever the boiler fires.
What a leak visit involves, if it turns out to be one
The circuit is isolated and pressure-tested to confirm and size the loss, then traced with acoustic equipment, thermal imaging and moisture mapping, and with tracer gas on a drained circuit where the run is buried. Nothing is opened until the leak has a location. After that we repair the pipework and reinstate the floor, wall or ceiling, rather than leaving you with a report and a hole.
The rate is £150 per hour, fixed before we attend, and if we do not find the leak you do not pay for the time spent looking. See boiler and heating leak repair, our pricing, or the wider boiler pressure hub.
