Alpha [E01] fault codewhat it means and how to fix it

E01 means the ignition sequence ran and the ionisation probe never saw a flame it could verify. Alpha appliances make several attempts before locking out, so by the time the code appears the appliance has already tried and failed repeatedly. What the code does not tell you is why, and there are four genuinely different answers with four very different costs. The one worth ruling out first, because it is free and because it accounts for a large share of these call-outs between December and February, is a frozen condensate pipe. A condensing boiler produces acidic water within a minute of firing, and if the drain is blocked with ice the condensate backs up into the combustion chamber and the appliance shuts down almost immediately. The others are a genuine loss of gas supply, a worn ignition electrode, and a gas valve fault — and only the first of those is something you can check yourself.

1. 1

   Check whether other gas appliances in the property work. If the hob will not light either, the problem is the gas supply and not the boiler — check the meter and any prepayment credit.

2. 2

   Go outside and find the condensate pipe: white or grey plastic, usually 21mm, running down the wall from the appliance towards a drain. Feel along it for a section that is cold and solid.

3. 3

   Pour warm water slowly along the frozen section. Boil a kettle and leave it ten minutes first, or mix hot and cold at the tap so it is comfortably hot to the hand.

   Never use boiling water. Thermal shock cracks cold plastic and turns a free fix into a plumbing repair in the middle of winter. Never use a heat gun or naked flame anywhere near the appliance.
4. 4

   Once you hear or see water running from the end of the pipe, go back inside and hold the reset button for five seconds.

5. 5

   If it lights and stays lit, the condensate was the fault. Get the external run lagged or upsized before next winter, because a pipe that freezes once will freeze again.