Baxi [E128] fault codewhat it means and how to fix it

E128 is flame failure, logged when the appliance establishes a flame and then loses it, repeatedly. Baxi documentation refers to frequent flame failure, with some sources putting the threshold at twelve occurrences before the code latches, and E129 covering a closely related repeated flame loss condition. The distinction from an E133 ignition fault is the part that saves time. On an E128 the burner definitely lit, so the electrode sparked adequately, gas arrived, and the valve opened. Something then interrupted combustion that was already under way. That narrows things usefully. The realistic candidates are a gas supply that sags under load rather than being absent, condensate backing up shortly after the appliance starts producing it, flue recirculation once the system warms, or a sensing electrode that loses a marginal signal as everything expands with heat. The most useful diagnostic is one only the household can perform: noting how long the appliance runs before it drops out, and whether that interval is consistent.

1. 1

   Time it over two or three attempts and write the intervals down. A consistent run time points at condensate; an erratic one points at gas supply or wind.

2. 2

   Test whether it fails sooner with a gas hob running at full rate. If it does, the supply is the likely constraint.

3. 3

   In cold weather check the external condensate run for ice and thaw it with hand-hot water.

   Never boiling water and never a heat gun. Cold plastic splits and you will have created a second problem.
4. 4

   Note whether it is worse on windy days — that is genuinely useful and nobody but the household can observe it.

5. 5

   Reset no more than twice and hand your timing notes to whoever attends.