Coastal edition exhaust manifold anodes

[estebanw]

Good day all, we have a 2018 GS22 Coastal Edition with 140 hours on it. It’s had probably 75% of the hours in freshwater. At about 90 hours we would start getting an error message saying “exhaust manifold water temp higher than expected“ and then it would shut down into idle mode. Engine temp was never above 168 on the vitals so we ignored the error message it would start up again but then Error message would sometimes come on again and put the engine in idle mode. sometimes when wake surfing and sometimes just when cruising around with minimal load on the engine. Engine temp was never over 168 on the vitals. We took the boat to our nearest Nautique dealer and they changed the sensors and tried to track down what the problem was but we continue to experience the error code and the engine going into idle. Unfortunately, they don’t have experience working on saltwater boats. What we just found out from the technician in Miami Nautique is that there are sacrificial anodes in the exhaust manifold of Coastal versión boats pre 2019 that need to be replaced at around 100 hours. This was not something that was in the manual or any other information available for that coastal version boat so I’m wondering if other people have experienced the same issue. Apparently the anodes as they break down can clog parts of the sensors or other ports in the exhaust manifold. Seems like a pretty crappy system which is why PCM has moved away from it for the 2020 models. Has anybody else had this experience and any information on how to clean out/swap the anodes?