False flame error code. RBL control box Riello

[Mike2007]

false flame error code (Riello)

This control box code is plaguing me as I'm trying to fix a Firebird Enviromax boiler.
The digital sensor has been replaced (special one) but still error occurs.
If you pull the sensor out whilst running the burner does stop.

 

[oilboffin]

Does it stop if you shine a torch at it. Bob

 

[oilhead]

If you disconnect the p/cell, does the burner start and then run to lockout? If problem of false flame persists, then C.box is suspect.