496 HO Sea Water Temp sensor location
 

I am trying to help out a buddy that has a 2001 496HO. He has been having some issues , as it seems to be going in to gaurdian mode at times. I connected the scan tool and the only thing I could find is that it says the lake/sea water temp is 431 degrees. I found the water pressure on the sea pump, coolant temp sensor under the heat exchanger, but where the heck is the sea water temp sensor?

I think there is one on each exhaust manifold, right under the bypass hoses... I know there is one plastic sensor on each manifold, wether or not this is the sensor you looking for.......

You are correct, there are the ones on the manifolds, but they show up under a different sensor in the scan tool, port & starboard sides, but the ECU is still showing 431 degrees. I read some thread that said the early models had a sensor on the PS cooler. I looked and didn't see any on there, but there is a lot of parts, hoses and wires back there, so if it's there I might have missed it. Hopefully someone on here knows the exact location so I'm not spending wasted time locating it.

Bumping this, someone has to know where this is located at! A quick thought, does the pressure sensor double as the temp sensor also? There are 3 wires going to it.

I could be wrong but it probably doesn't have one. I believe this is an auxillary function that doesn't result in a guardian mode. My 496 doesn't have one.

+1
I was told that that was the default setting when it's not used
your best bet would be to call ray from raylar

All 496's have one sensor on each manifold. It's threaded into the surface just around the area where the riser mounts. The early ones were plastic and blend in with the manifold.. It has a 9/16 hex head.

The best replacements for them is the newer brass style because the old ones would break or fracture and sometimes you can't see that it is broken unless you remove it.

New part number is: 885342002 and they retail for around $26 each. Don't use the plastic ones even if they are available. It's a critical part to be made of plastic because it can put you in guardian sometimes when it's actually not hot..

They're mounted in the exhaust to help prevent operators from burning and melting the rubber exhaust hoses etc. Once it gets too hot it will sound alarm.

Also, on closed cooled engine, if there is a water flow restriction the exhaust will almost always get hotter and quicker than everywhere else so the idea was to put the sensor where it could catch rising temps asap..

I believe the sensors on the exhaust manifold do not throw a lake /seawater temp alarm but port and starboard manifold temp alarm. As said before it's a different code.

Yup my bad... I never heard of anyone using that option. I actually forgot about it because it's a rarely used SmartCraft option that seemingly very few people pay to have.

When I think of seawater temp I think of raw water cooling. There is a separate transducer for that data link.

Kick me :lolhit:

Thanks guys, it sounds like we can just ignore that sensor then. I will have him run it and check for codes and sensor temps after it warms up. It had a problem where it would cutout trying to get on plane, but we changed the crank sensor and that problem appears to be fixed. It wouldn't start at the end of a day, but it was hot out, so maybe it was vapor locked. I will update when I find out more info and we do more trouble shooting..

Most likely you don't have the lake/sea water temp sensor/transducer installed on the bottom of the boat. so this would be the default reading from the boat's transducer being unplugged.

The lake/sea water temp "sensor" would be located inside thru hull transducer going thru the bottom of the boat to read the actual water temp of the body of water the boat is sitting in.

The PCM is designed to ignore this reading and a few others as far as engine guardian mode goes.