I dnt know much bout k12s, bt crystal round the corner had same problem and was down to the crankshaft sensor dnt know if that's the same as cam sensor? She replaced hers and worked perfect again
Wdidt? Washed and polished her so lookin all nice and shiny, come back 20 minutes later and birds **** on it :( happend 3 times now, think they do it on purpose.