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I have a 2015 SD 350 V Drive …my...

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I have a 2015 SD 350 V Drive …my Kohler 5EKD generator is throwing an AF error code. Sometimes it runs for a while (2-3 hours) sometimes shuts down within minutes. Replaced 02 sensor. A buddy with a similar unit in his 310 says it might be the fuel pump…thoughts?


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I have an older Kohler that doesn't give error codes, but when I was having the same symptoms otherwise, iit turned out it was low on oil. After I checked the dipstick and saw it was low, and added some oil, the problem went away. Could just be the older Kohlers consumer more oil than yours, but it wouldn't hurt to check before doing anything expensive.

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Does it do that while running or does it make a difference? If it is a bit low on oil, it can shut down when you are planing off because the sensor sees low oil or pressure.

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The AF code on my older 5Ecd says it’s a auxiliary fault. Could be a problem with the remote control unit

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Going to update everyone as this may be helpful to others in the future…hired a generator specialist to help solve this issue and so far it has been a nightmare.
1. Threw AF codes; he says AF codes are either monoxide sensor in cabin or auto fire suppression. Replaced cabin sensor (a total drag because the old fireboy was discontinued)
2. Then we got Vu / Uu codes; replaced oxygen sensor and low pressure fuel pump. Worked for a day and then same codes going to replace high pressure fuel pump, spark plugs, fuel injector, water impeller, fuel filter says problem is ethanol in old fuel. This is a total drag. I’ll let you all know what happens.

Guest Contributor
I have the same 5EKD genset on my 2016 370. Struggled with the AF fault shutting down the generator since we took the boat on delivery until I traced the problem to the boats wiring harness the generator plugs into.

Kohler insists the manufactures use the Kohler wiring harness, but Brunswick uses and makes their own, less expensive version to plug the generator into. Kohler knows all Brunswick boats may have this problem with their generators.

So short of rewiring the entire generator, you need to find where the shirt is happening. I you pop off the top cover plate on the generator you will see where the Brunswick wiring harness plugs into the back housing in the generator (it’s a male/female plug). On my boat, the loose wire was in the Brunswick male end of their wiring harness that plugs into the genset.

How I found it was, I unsnapped the Kohler female wires from the white housing on the back plate of the genset and routed those wires through the open cover plate (access cover). Then I plugged back in the Brunswick’s wires into it and started the generator. This allowed me to be able to move the wires around until I could re-create the short and trigger the AF Fault.

What I found, if I leave the Brunswick wiring harness torqued into the hard angle plugged into the back of the generator as designed, it creates a short. If I remove the generators female connector from the housing and simply route that wire bundle though the open top, when plugged in that freely, no short and problem fixed and the generator runs great.
That makes it so I cannot use the generators cover plate because there is a wiring bundle out the top, but who cares. It runs great this way, and with no cost it fixes the problem. I was a little worried that in rough seas the wires would jiggle around, but that has never happened after 3 years of rough Lake Superior. The male/female snaps tight.