2000 Super Sport with GT40 Check Engine Light

[NautiqueJeff]

Here's the water temp switch location.

[Need2SkiT]

You guys are all awesome! So assuming it’s not the oil pressure sensor, where do I look for the water temp sensor if I get to the lake and it’s still acting up?

[Need2SkiT]

Here's the water temp switch location.

Is that the distributor cap that it’s directly over? I’m back outta the boat but I see the plug wires. Just wanting to see where I should be looking. Thanks again!


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[NautiqueJeff]

Yep, you got it. Look for the green wire.

[Need2SkiT]

Yep, you got it. Look for the green wire.

Thanks again Jeff! love this group and I definitely owe you a case of beer.


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[Need2SkiT]

Had a chance to run the boat over to the lake this morning. Jeff, you were right. Oil pressure sensor it was. It ran better than the day I bought it. Thanks again to everyone that was so helpful. Now time to order a new sensor.


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[OREGON85]

Same boat, same engine, similar problem. Mine doesn’t go into limp mode but the light is on. In the screenshot it says limp mode comes on at 200+ temp or 5 PSI or lower oil pressure. Do limp mode and the check engine light have the same parameters? My temp was around 160 and my oil pressure was 30 at idle. Seeing oil pressure and normal temperatures we kept going and it ran great. Any tips here? Also, I am not quite sure I understand the role of the oil pressure/temp switches relative to the sensors.

[Jonny Quest]

The GT40 engine has an oil pressure gauge and sending unit. Also has a temperature gauge and sending unit. These are only for the gauges on the dash. The dash gauges tell YOU (operator) certain engine parameters. These sending units and gauges do NOT send the ECM (engine computer) any information.

The engine also has an oil pressure SWITCH and an engine temperature SWITCH. These have nothing to do with the gauges on the dash. The oil / temp switches send information to the ECM. The ECM analyzes at the incoming information and if the information coming from the switches is outside the programmed parameters (too high or too low), then the ECM puts the engine into limp mode. If the switch is failing, then it can send bad info to the ECM, which could then put the engine into limp mode and turn on the Check Engine Light. The purpose of limp mode is so that you can "limp home" without totally destroying the engine -- that's the theory

If you go back and read this entire thread, you will see where the oil pressure switch is located, along with the water temperature switch. To test if the switch is failing, simply disconnect the wire coming from the switch. You gauges should continue to work, but the ECM won't be able to see any information coming from the switch. Your C-E-L should not be lit at this point. Keep in mind that you have disabled the "safety net" of the switches, so be extra vigilant on your gauges.

JQ

[OREGON85]

That is all very helpful. Thank you.

One clarification: why is the light coming on but not limp mode?

[Rusty Barras]

you can run a code scan and pull the exact code that is triggering the light. i run scans on mine every year. sometimes there are codes not tripping the light. you can buy a reader on amazon or hook up a 12v test light.

typical KOEO procedure and hookup
https://www.therangerstation.com/tec...ipped-engines/

scanner - optional
https://www.amazon.com/INNOVA-3145-F.../dp/B000EW0KHW

also here's the marine gt40 manual. the procedure starts on pg 3d-2. the codes are on 3d-17. The manual has step by step instructions depending on the code you pull
https://www.planetnautique.com/Corre...e%20Manual.pdf