Hey guys I need a little help determining how many camshaft position sensors I need I am working on a 2005 audi a4 cabriolet 3.0 it has 4 sensors and I have 3 error codes all for sensor b but 2 being for bank 1 and one being for bank 2 the codes are po365,po366, and the one that is throwing me off is po391 for bank 2. Thanks