For approx 20 secs, if this fails, its probably the thermocouple,
if u take the fridge out, look at where the flame comes out, there will be a wire, solid copper, that sits in the flame, this keeps the gas valve open,
usually its just a carbon build up on this wire, which can be cleaned off with a bit of emery/fine sand paper.
happened to us out on tour, so i cleaned it with half of the wifes emery board nail file. worked a treat after.
hope that works,
Paul
ps when u finish cleaning the wire, it must sit in the flame but no touch anything around it, ie any metal casing
Mine does this and i find is that immediatly afer i let go of the knob or brass shaft i pull it. flame stays lit then. This seems to work every time for me.
S
either thermocouple or gas reg actuating valve , thermo couple cheap to buy from screwfix , make sure it sits in the flame correctly especially if van on a slope .