If your ski is giving you a warning on oil and going into a limp mode then you are doing the right thing by taking it in for a service they will run a check on oil pressure and make sure it is within specs.the sensors do go bad but I would never just replace the sensors and then ride the ski on water to see if it's fixed.you want to check your oil pressure at block and head must have oil pressure within spec at both places.red warning and going into a limp mode could be bad sensor but if sensor is good and you do have a pressure problem you are causing more and more damage every time you run that engine this is just my opinion and I'm sure it differs from others but remember basic rebuild 2500.00 3300.00 at most dealerships or 300.00 service bill to check oil pressure now and make sure their is no problem.