View Full Version : Engine Computer Question

Tall Cotton
04-29-2012, 10:45 PM
My Mercruiser Black Scorpion DTS gave me a "Starboard Oxygen Sensor Malfunction" alarm today. I'm pretty sure it's aft of the cat becasue the engine is running fine and the info goes on about emissions.
Here's the question: If I replace the sensor, and it remedies the problem, will the code clear and the alarm stop, or do I need to drive clear to the other side of the lake, take the boat out and drag it 40 miles just to have a tech plug into the computer, tell me, "yep, that's the problem" and then charge me big $ to clear the code?

04-30-2012, 12:27 AM
You could buy a scan tool or the computer software from Diacom and see what is really going on with the engine and clear all codes that have been set in the computer memory. What your going to spend to have a merc tech do it

Tall Cotton
04-30-2012, 01:09 PM
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So where would this fuse be located - in line from the sensor, on/in the boat relay/fuse box or a separate engine control relay/fuse module near the engine?

Tall Cotton
05-13-2012, 08:49 PM
Update. Being that it was still under warranty I took it to my nearest (and up to date) Mercruiser service. Multiple sensors and checks later, they have been troubleshooting for over a week so far and the next step is a conference call with the engineers because to quote the Mercruiser tech in Fon du Lac, "I've never heard of that happening before!" To sum it up, everything works fine for two minutes and then the computer shuts off the Port sensors and goes into default mode. It still runs fine except the alarm goes off every minute.
"I hate computers!" -Sam Neil, Jurassic Park

05-18-2012, 08:07 AM
Ughhh, the "joys" of EFI. It is nice when it works, but when something goes wrong (usually for no reason) it is a nightmare and NOBODY knows what to do, even Mercruiser. Trail and error becomes the way to fix these silly things. Give me a one wire Mallory distributor and a carb any day. I can draw the entire wiring diagram out of my head on a napkin in 30 seconds (and therefore fix it almost as fast)

05-19-2012, 02:28 AM
Computer, computer? Ain't got no stinkin' computer on my old '88 22C....some problems I got, but this isn't one of them. ;-)