Baxi [E135] fault codewhat it means and how to fix it

E135 sits between E134 and E154 in every Baxi digital-display table with the entry "Interruption of gas supply (internal error)", and the 600 and 800 manuals bracket it with its neighbours: "133, 134 and 135 indicates that the gas supply has been interrupted, ignition has failed or the flame has not been detected." It is also on the list of codes those manuals say can be relit from the panel by pressing Reset for one to three seconds. The two words in brackets are what separate it from the others.

E133 is a failure to light, E134 is the valve open with no gas arriving; E135 is the board reporting that its own gas control did not behave as expected — the valve did not respond, or the circuit that drives and monitors it returned a fault.

Baxi's professional table simply calls it "Internal error". That does not mean the supply is irrelevant: the boiler cannot always tell a valve that would not open from a valve that opened onto an empty pipe, so the ordinary checks (is the gas on, does the hob light, is the cock under the boiler open) still come first and are still free. But an E135 that returns after one reset with gas confirmed at the property is an electronics fault rather than a supply one, and the 600 Combi fault-finding sequence for the ignition group ends at "check all PCB connections; if this has no effect replace the PCB". It is printed only on the digital-display generation.

1. 1

   Check the gas is on: light the hob, check any prepayment meter, and look at the isolation cock under the boiler.

2. 2

   Press Reset for one to three seconds, once. Baxi list E135 among the codes this relights. If it returns, or if it keeps appearing, the manuals say further investigation is required — that is an engineer.