[Public-List] Diesel question

[John Johnston via Public-List]

Ahoy Mates! I have a Westerbeke 20B Two in my Alberg 30. It has sat idle for the last ten weeks but has always run fine. She started up easily but when the preheat button was released the low oil alarm continued to sound. The oil pressure gauge showed 50 psi, raw water was pumping through the system, she ran smoothly. I shut it down, double-checked oil levels, all good, tried it again with the same result. Could this be the result of a failed sensor? Would welcome input or suggestions.