I just took delivery of a boat with a pair of 3406e Cats, vintage 2001. On the delivery, one engine kept throwing an over speed number 2 sensor fault bearing Code 273. There was no noticible engine drop in performance. The fault came up sporadically, sometimes once every 10 minutes and then again two hours later. The prior owner said he replaced the overspeed number two sensor. I do not know where to start. Do I now replace both the overspeed number one sensor and the turbo boost pressure sensor? Sorry for the questions but these are my first Cats. Thanks.