I have got the same prob on my motorhome, I think it might be the pilot light that has a yellowish flame, I cannot get anyone to fix it, so I have gone to Maplins and bought a can of air duster and blasted the pilot with it, absolutely loads of cruddy bits have blown out, so much that I had to get the hoover out to pick it all up, and I now have a blue flame, so I am hopeful of that fixing the smell prob as at the moment the gas smell has gone.
dj, June 2009
