Hello , Here to answer automotive questions and make you feel comfortable and become familiar with your product
either the sensor is failed or the timing belt is old and stretched causing the timing marks to be off by a hair or the cam timing is off. can you post the remainder of the fault description. I need to read that.
Which sensor B1 or B2
if the marks are ok the sensor is failed but will need to know which side
you must rule out the working parts in order to find which is non working.
the ony way cam timing is off is if you have had the cams removed and re installed improperly other wise the sensor or the wiring or the belt is the problem
how is it going ?