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I've decided that O2 sensors are consumables!

M

metal-chicken

Regular Contributor
Yesterday I fitted a new O2 sensor to my 225 and it's back to running perfectly again (it was giving a code 1 alarm after extended idling, e especially after a longish run)

The engine is an ’06/'07 and has the updated sensor and ECU - I don't know about the modified exhaust tubes but I would have thought that they have been done seeing as the aforementioned upgrades have been done.

This is the second O2 sensor that I've fitted in 3 years and I think that they just don't last..... Especially the heater circuit.
It seems logical that if the heater circuit has to come on when the engine is idling, then the more idling you do the quicker the heater circuit will die.
So for those of you that do long runs on a regular basis then you may not have much of a sensor problem - but those who don't get to do long high speed runs may need to replace their sensor more frequently.

As an experiment I'm now going to swap the OEM sensor out for an NGK sensor which costs half as much to see how long it lasts. I can easily swap back to the Honda sensor if needed.
 
You are right about the heater, In an auto application the exhaust would stay hotter for longer and there wouldn't be extended idle. I can't see any problem using the NGK equivalent, it should be fine
 
It could also be a sign of other issues? Is the charging system working properly do you have a volt meter you can monitor battery voltage real time? If you do alot of slow speed operation a nice kicker would save wear and tear on the main. Just hook them in tandum!
 
Power system seems to be just fine - charging OK while idling. We don't do a lot of slow speed stuff, it's either on the plane or idling and i think idling does the damage.

We don't get to put a lot of hours on every year anyway which I think is also a contributing factor.
 
Metal Chicken - here are the serial numbers of the engines that did not get the modified exhaust tubes.

BF 225A
• BAGJ 10000001 to approximately 1500324
• BAHJ 10000001 to approximately 1500022

Let us know about the NGK HO2 sensor. Can you post the part number?
 
My experience has not been good on the 250s, I had trip 225s for nine years never had an issue, Repowered with trip 250s December 2016, 80 hours later all three have had to be replaced.
Dealer tried to give me some crap about them not being covered, I wasnt buying that.
 
Well theoretically my engine (BAGJ1404700) didn't get the modified exhaust - but might it have been done with the ECU/Sensor? Unfortunately we don't have an easy way to get an engines warranty history here in the UK for some reason.

The NGK part number is 932-24008. It should arrive by the weekend and I'm hoping to be on the boat on Sunday so will fit it straight away...... we'll see if it's still going by Spetember as we make most use of the boat during late July and August.
 
Not had a chance to fit the alternative yet - but I'm down at the boat on in a couple of days for a few weeks so will get it fitted and see how it goes.
 
Well, two weeks into my trial of the non-original O2 sensor and it's going fine.
I did have one alarm but that was almost Immediately after starting the engine so I'm ignoring that because the sensor hadn't had any time to heat up. Restarted the engine and clear ever since.
Will keep you updated.
 
Good to hear.

I did a search on that NGK HO2 sensor on US sites. Only found one hit - $175 USD. Compared that to the OEM on Boats.net for $207 USD. Doesn't seem like much of a savings for an after-market sensor.

Were your costs a lot different there in the UK?
 
Thought I'd replied to this before but it seems not....

So the sensor I'm running is a Walker Products 932-24008 which cost £90 delivered here in the UK.
I've just pulled the boat from the water for the winter and I've not had a single O2 alarm issue so far - the boat is currently at the yard being bottom painted for next year and when I get her back home in a couple of weeks I'll pull the spark plugs and post pictures.
 
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12 Month Update:

So the boat went back in the water 10 days ago and ran fine with no alarms or O2 issue. The next day I went out again and the O2 sensor alarm started going again. I tried giving it a good run to get plenty of heat into it just in case it made a difference but didn't idle long enough at the end of the run to test this out, but I was smelling a bit of fuel in the exhaust so I think it was running a bit rich.

Back on the boat yesterday and the alarm went off again - tried another decent run but no difference so I replaced it with a barely used OEM sensor that I had and all is now good again.

So.... for 12 months the pattern sensor worked fine - the same length time as I'm getting from the Honda sensors, but a lot cheaper! This winter I will dig into the engine and see if the modified exhaust tubes have been fitted - if not then I'll do them.

I'm not really surprised that the pattern sensor died - in fact I'm probably quite happy that it lasted the same time as the Honda sensor.

I do wonder, though, if our pattern of use (used from June - Sept then sat over winter) has some bearing on the longevity of these sensors? Maybe they just like to be in fairly constant use.
Or maybe it's just the exhaust tube design.

[I should add that a few weeks before the boat went into the water I ran it in a large tank for about 30 mins - almost all idling - and it was fine. So maybe this points more to the exhaust tubes]
 
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Metal-chicken - it is my understanding that these sensors are exceptionally sensitive to water vapor/high humidity. So, that could be the issue. Just speculation.

I've got 2100+ hours on my 2007 with the revised exhaust tubes and the original HO2 sensor is still in there. No alarms and no codes. So, eventually, you're probably going to need to replace those exhaust tubes.

The NGK site says that the 24008 HO2 sensor has been replaced by the NTK 22082 sensor. But when I looked at that one, it doesn't seem to match up with the OEM sensor. Do you have any insight on that?
 
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