I had a similar problem on a Yamaha 150. After putting up with it for a long time, I finally called Rockwall Marine and now I have an appointment for next week. They said there are two sensors that are suspect, but can only diagnose for sure with a thorough test. A couple of years ago, I checked on the price for the sensors (parts only, no labor). They were about $300 for the pair, but there are other problems that could be causing the low oil light and the rpm failsafe. At that price, it's not worth me trying to replace parts till I find one that solves the problem. I've had work done at Rockwall before and they are good about getting it fixed right in a very reasonable time. So, I be back on the water shortly.
Edited by jfe (03/09/18 09:36 AM)
Edit Reason: error