O2 sensor failure on Indmar 409 SS series

HalfKiwi · **Posted:** Tue Oct 30, 2018 4:40 pm

Has anyone else had multiple O2 sensor failures. I have had mine changed four times now and they keep loading up with black soot (carbon).
The boat runs perfectly, water temp/oil pressure/idle/top speed.
The alarm keeps sounding and throwing the O2 sensor codes.

What was your fix.

dustinjean · **Posted:** Wed Oct 31, 2018 1:34 am

What octane are you running and ethanol or non ethanol gas?

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dustinjean · **Posted:** Wed Oct 31, 2018 1:36 am

Also what year? ecu might need a reflash to fix afr issue

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A22owner · **Joined:** Mon Jul 28, 2014 10:25 am **Posts:** 208

Surf real heavy?

I recommend running the boat WOT at the end of the day with no ballast. It will help burn the carbon off.

Wilbur · **Joined:** Mon Dec 15, 2014 9:04 pm **Posts:** 62

A22owner wrote:

Surf real heavy?

I recommend running the boat WOT at the end of the day with no ballast. It will help burn the carbon off.

Wouldn't idling cause carbon buildup more than running heavy?

I would think surfing or wakeboarding heavy at about 4k RPM would reduce carbon from building up.

A22owner · **Joined:** Mon Jul 28, 2014 10:25 am **Posts:** 208

Wilbur wrote:

A22owner wrote:

Surf real heavy?

I recommend running the boat WOT at the end of the day with no ballast. It will help burn the carbon off.

Wouldn't idling cause carbon buildup more than running heavy?

I would think surfing or wakeboarding heavy at about 4k RPM would reduce carbon from building up.

It can. One of the issues with people who surf heavy is that they are lugging the motor for very long periods of time. It runs slightly rich when this happens and this cokes the O2 sensors up. Take it easy after lugging it and putt around and it never gets hot enough to burn the carbon off effectively.

HalfKiwi · **Posted:** Sat Nov 10, 2018 7:35 pm

Thanks for all the input, I run 91octane, we do surf mostly. Tried running hot laps at 4500rpms. Still loaded
up. Turns out the Stainless Steel heat exchangers develop small cracks that develop slowly. Out of warranty.
I will be looking for something other than Indmar on my next boat.
Only 247 hrs when first started.

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O2 sensor failure on Indmar 409 SS series

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