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2017 Txi monsoon 409 getting Coolant Overtemp alarm/ CHT Higher than expected 2 code

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I have the monsoon 409 engine in my 2017 Malibu Txi. I have replaced all four O2 sensors as well as both water temperature sensors. I am still getting CHT Higher than expected 2 code along with Coolant Overtemp alerts and occasional "limp mode". The engine temperature indicates in the 160's and the lake water temp is in the low 80s. There really is no apparent reason why the engine is throwing codes, the water flow is fine.

Additionally, my friend with the same year/boat/engine is having the same problems (new boats to both of us)

.So that makes me wonder, is this an issue with that year's engines? Is there a known fix? Any information would be appreciated, the wait for my Malibu mechanic to look at it is 8 weeks. 

My thought is that, when the engine sits after a set, the warm engine heats up the water in the casing and then when I start the engine for the next set the water temp sensors sense the hot water in the casing and throw the code. Anyone have this problem.

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  • 3 weeks later...

SPN 110  FMI 0



As it turns out, my friend took his to the dealer. After 11 hours of troubleshooting and replacing parts (including parts he had just replaced) and $1300, his code is gone. He says the dealer doesn't know what fixed it and his bill of service just says "diag overheat", so no useful information there.

I did take the boat out to the course the other day. I had a theory that after running a skier for a set and then sitting while another skier/boat ran a set, the engine would heat the water in the coolant casing, and then when I started the boat for the next set, the water temp sensors would read the high water temp and kick off the alarm. So after starting the boat I would rev the engine for about 20 seconds to get cooler water flowing past the water temp sensors. This seemed to work for the most part. Makes me wonder if there are sensors which are less sensitive, or the algorithm of the computer is too sensitive. I sent an email to Crusader regarding the issue and they never responded back.

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The SPN 110 FMI 0 sets when the engine coolant temperature is above 210 deg F and the engine RPM is above 600.  If the exhaust coolant sensors where also reading above the normal temperature threshold then you would also get a SPN 441 or 442 code.

If you are only getting SPN 110 FMI 0 or 15 then the engine coolant temperature is getting too high and not the exhaust manifolds.  Even though any leaks or blockages in the system can cause this problem, or a worn sea pump impeller, I would focus on the engine cooling first.

Somewhere around 2015, Pleasurecraft started using a different thermostat.  They provided a service advisory, SAP2016-01, that recommended replacing that thermostat with the earlier version of it, PN R026002, if replacement was needed during service.  It may be worth trying that first.

If the coolant temperature is actually much lower than 210 deg F when you get the alarm, then there is likely an electrical problem.  Checking all of the power and ground cables at the engine would be important.  The engine and exhaust temp sensors are interchangeable, so you could swap the sensors to see if the problem follows the sensor or remains the same.  Also, check the harness plug to the sensor for wear or damage.

This is an example of a worn connector on a Pleasurecraft temp sensor harness plug.




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