Baxi [E09] fault codewhat it means and how to fix it

E09 opens every Baxi digital-display table: "Gas valve connection cable". It is shown with a leading zero on the display and Baxi's professional page calls it "Gas valve connection fault". The 600 and 800 manuals put it in the group where "09 followed by 15 or 384 indicates possible faulty components", list it among the codes that can be relit by "pressing the Reset button for 1 to 3 seconds", and in the fault-finding flow give the same instruction as for E15: "If 09, 15, 110 or 384 is flashing or re-occurs regularly, check all PCB connections. If this has no effect replace the PCB."

The code is about the wiring between the control board and the gas valve, not about gas. On these boilers the valve is driven and monitored through a plug-and-cable set, and the board checks that circuit before it will attempt ignition; an open circuit, a connector that has worked loose, or a damaged cable produces E09 before any spark is made. That makes it a relatively cheap fault when the cable really is the cause and a more expensive one when the valve coil or the board has failed.

There is nothing for a householder to do beyond a single reset, since the components are inside the sealed case. Baxi do not print E09 on the selector-switch Duo-tec HE or Platinum, which report gas valve problems through E133.