Engine light 99 SN

[JAMES123abc]

Hey everyone! New here and new boat owner as well. I have a 1999 correct craft air nautique. The engine light keeps coming on irregularly. I’ve been told it’s a “dummy light” and that there’s possibly only a hand full of sensors that could be triggering it. My question for you guys is what electronic sensors are there on this boat. It has the Ford 351 Windsor I thinkkkkk. I’d like to replace allll sensors given they probably never have been. Oil pressure? Oil temp? Etc...? Thanks in advance!

[THE HECKLER]

replaced both my water temp and engine oil pressure sensors. was going in to limp mode with the bad water temp one. MIne is a 98 GT-40 FI engine. easy items to replace. used 1998 ford 150 for reference at the parts store. however if it hasn't been running badly you may just be low on oil. could check by disconnecting one at a time to see if that makes a difference.. i am a backyard mechanic - not a pro!

[NautiqueJeff]

Very simple. Only two things can activate the check engine light / Limp Mode in a GT-40. One is an overheat condition being sensed, and one is a low oil pressure condition being sensed. If you really are experiencing either of those conditions, you need to figure out why. Sometimes the switches that control the limp mode fail though, and activate limp mode even though there is no real issue. This would cause your gauges to read normal readings, but the switches for the SLOW system are signaling a problem, even though there is none. These switches are SEPARATE from the sensors for the gauges.

My bet is that the oil pressure switch has failed. You can disconnect the wire from that switch, and that should allow you to run the boat normally until you can get a new switch. It may also be the water temperature switch, and same deal with that, just disconnect the wire until you can get a new one and the boat will run fine.

Here's the oil pressure switch:
https://www.nautiqueparts.com/produc...nd-gm-to-2006/

Here's the water temperature switch:
https://www.nautiqueparts.com/produc...-mpi-r020014a/

We're talking about the SLOW system here. See diagram below.

These are the ONLY things that can trigger limp mode. Nothing else can do it.

[JAMES123abc]

Thank you for the input. Just to clear things up before I go ordering parts. I’m unfamiliar what a GT-40 is but presumably what I have? Or another boat with a similar or same engine?

[NautiqueJeff]

The SLOW system works the same on all engines of that era.

[JAMES123abc]

I see thanks again. I’ll reach out and give you an update or if I have further question. Cheers!