Baxi 80e flame failure

[pmd2579]

baxi 80e flame failure?
I have a problem with my baxi combi boiler,it shows flame failure after a few seconds when firing up, however without the sealed case off it works fine and with it on but screws not fully tight works fine. This is only on heating,the hot water works fine. The pipes leading to the pressure switch are clear and the pressure switch has also been changed. the flue is also clear, any ideas??? The venturi and pipes have been replaced

 

[gasandoilman]

why are you taking the sealed case off a gas appliance??
get a gri into check it as leaving the cover loose could allow co to come into the room.
the flue sounds like it could be faulty and allowing gasses back into the air intake not something that should be advised for a housholder to check.