Kohler 5ECD Error Codes LOC and UU

estebanj

New Member
Apr 2, 2007
590
South Florida
Boat Info
260 Sundancer
Engines
350 Merc
On my last outing, my generator shut down while cruising at idle. The error code was UU, which is undervoltage (I believe at the source batteries). It sat for a while then I got LOC error code, which is loss of coolant (no leaks or actual loss).

I took the impeller out and one vane was missing, so I installed a new impeller.

Generator started OK, but today after 30 minutes or so it shutdown again. The error code again was UU. When I got back to the marina, I attempted a restart and got LOC again. It cranks and tries to start, but shutsdown quickly after less than 5 seconds or so.

I can see water coming out the exhaust side, and there is coolant in the reservoir.

Any hints before calling the Kohler dealer or MarineMax?

Could the broken (missing) vane be stuck in the heat exchanger and that's what's causing a problem?

Could my batteries be bad and that's what's causing the UU code?

Are the 2 codes LOC and UU somehow related?

Engine starts and runs fine from the same batteries.

Thanks,

Esteban
 
Do yourself a big favor and call the Kohler dealer, not MarineMax. Your generator is too complicated for guesswork. Plus, it may be a warrantable repair.
 
On my last outing, my generator shut down while cruising at idle. The error code was UU, which is undervoltage (I believe at the source batteries). It sat for a while then I got LOC error code, which is loss of coolant (no leaks or actual loss).

I took the impeller out and one vane was missing, so I installed a new impeller.

Generator started OK, but today after 30 minutes or so it shutdown again. The error code again was UU. When I got back to the marina, I attempted a restart and got LOC again. It cranks and tries to start, but shutsdown quickly after less than 5 seconds or so.

I can see water coming out the exhaust side, and there is coolant in the reservoir.

Any hints before calling the Kohler dealer or MarineMax?

Could the broken (missing) vane be stuck in the heat exchanger and that's what's causing a problem?

Could my batteries be bad and that's what's causing the UU code?

Are the 2 codes LOC and UU somehow related?

Engine starts and runs fine from the same batteries.

Thanks,

Esteban

This might help you out... from the Kohler Manual. Check the "real" coolant level by taking the cap off the top of the engine - engine cool of course.

http://my.jetscreenshot.com/81/20090530-wui1-591kb

Hope this helps! :grin:
 
Last edited:
There have been a few issues with these generators that I think everyone should expect to deal with at some time. When speaking to my service person, he has had to make these changes on quite a few.

1) Your LOC most likely could be caused by the "older version" of the exhaust. I had this problem also, and there is an "Exhaust KIT" that is needed. This generator has a cataletor convertor that runs hot, so it is cooled by the seawater. however, in the initial design, the tiny holes for the water to pass through were too small and got clogged up. Especially if you boat in dirty water, or water with a lot of algae in it, as there tends to be sometimes in FL. The new exhaust has larger holes, and i have not had problems since.

2) I had a relay problem on the starter relay that was in theory caused by too small a relay for the new fuel pump on this design. It was fixed, and have not had a problem since.

3) I had a bad CO2 sensor that needed to be replaced. it would cause the geny to shut down.

4) When i first got the boat, the batteries were dry, and my generator would shut down all the time or UU, so you probably have bad batteries also.

So after 300 hours, and using it year round i expect to run into all the problems eventually. Other that that, it works great.

My Marinemax actually referred me to a local marine electrician that has been great in dealing with called Gulf Coast Marine Electronics. They service a ton of these here.
 
I believe the solution to this has finally been found... bad pressure sensor on the raw water side. It's the small round sensor connected to the heat exchanger with 2 cables to it. Specially in dirty or salt water, the sensors malfunctions (gets dirt or corrosion in it) and tells the generator to shutdown due to lack of proper water flow.

I replaced it today and it ran OK. I'm 99% confident on the fix. The remaining 1% will come later next week when I run the gen for a longer period of time.
 
I believe the UU would indicate gen. not putting out the correct voltage. The battery is used for starting. Once started the battery has little impact. However, I'm glad you found the issue.
 

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