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Discussion Starter · #1 ·
Hello again, Whilst I revitalise my old girl (K1200GT 2005), I have been reading about the oxygen sensor. Now I don't have a specific issue but have read that it could be changed after 30k miles or so and my old girl has done 98k (I've had her from new), and it's the original oxygen sensor. When she was a year or so old, I aquired a complete exhaust system which I stored. That has an oxygen sensor on it I could swap out. Is it worth it? I'm told you can lose performance and it can run rougher, but that kind of thing creeps up on you and I am unsure if it has lost performance really. One for the theory of leave it unless it looks broken, am I wasting my time replacing it?
Below are some things I found that can happen if it's worn...

Here are some possible indicators of O2 sensor wear and tear:
  • Decreased gas mileage: A failing oxygen sensor could cause an increased amount of fuel injected into the engine, resulting in significantly lowered fuel economy.
  • Engine misfiring: Rough idling and engine misfiring are common signs that an O2 sensor is failing. Combined with a check engine light, this can be an indicator that you need to have the part checked.
  • Drop in engine power: An air/fuel mixture that isn’t regulated properly can cause performance issues with the engine, including difficulty accelerating or reaching full power. This can be caused by a worn O2 sensor.
  • Rotten egg smell: Excess fuel in the engine can produce the smell of rotten eggs that comes from sulfur. Excess fuel could be due to a failing O2 sensor.
 

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Hello again, Whilst I revitalise my old girl (K1200GT 2005), I have been reading about the oxygen sensor. Now I don't have a specific issue but have read that it could be changed after 30k miles or so and my old girl has done 98k (I've had her from new), and it's the original oxygen sensor. When she was a year or so old, I aquired a complete exhaust system which I stored. That has an oxygen sensor on it I could swap out. Is it worth it? I'm told you can lose performance and it can run rougher, but that kind of thing creeps up on you and I am unsure if it has lost performance really. One for the theory of leave it unless it looks broken, am I wasting my time replacing it?
Below are some things I found that can happen if it's worn...

Here are some possible indicators of O2 sensor wear and tear:
  • Decreased gas mileage: A failing oxygen sensor could cause an increased amount of fuel injected into the engine, resulting in significantly lowered fuel economy.
  • Engine misfiring: Rough idling and engine misfiring are common signs that an O2 sensor is failing. Combined with a check engine light, this can be an indicator that you need to have the part checked.
  • Drop in engine power: An air/fuel mixture that isn’t regulated properly can cause performance issues with the engine, including difficulty accelerating or reaching full power. This can be caused by a worn O2 sensor.
  • Rotten egg smell: Excess fuel in the engine can produce the smell of rotten eggs that comes from sulfur. Excess fuel could be due to a failing O2 sensor.
If you are riding the same K1200 for a long time, you would notice change in fuel mileage like I do. I do a rough calculation when filling every tank and reset my trip meter to Zero. Worsening fuel mileage of at least 20% or more are common when the O2 sensor is going downhill or is unplugged. On modern motorcycles having these types of O2 sensors, a life of 60,000 miles (100,000 Km) can be expected as an average.

They can last longer - it depends on many variables (long / short rides , city driving , maintenance , fuel , engine oil consumption). I did change mine at about 70,000 miles (110,000 KM) because of behavior change in mileage AND ALSO based on data from GS911.

Do NOT buy a new O2 sensor before you have seen the graph in real-time with engine warmed up (or while it is warming up). Just looking at static values variations is pretty much useless as they can vary too fast of randomly on most multimeter. A GS911 diagnostic tool (like the dealer's computer) can show a real time graph.

The Graph , studied for 1 minute or more, is the only way to check if O2 sensor is really working as it should.
You should also vary throttle (neutral , on center-stand) for short period to see if response is correct: quick opening of throttle to 3000 RPM for very short period should produce O2 graph fluctuation , then it should go back to its normal up-down range it had before. If all you see is a flat line , it may also have been unplugged (or not properly re-connected) by previous owner.

If-and-only-if we can confirm you need a new O2 sensor, do not buy from dealer at crazy prices. The same BOSCH O2 sensor is available from various sources at much lower price.

See this article on the GS911 web site for a good / simple technical overview of testing an Oxygen sensor: Lambda — HEX Code
 
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I just went through this O2 sensor deal onm my 2002 KRS recently. My original sensor lasted 110,000 miles. Fuel mileage went down to 20mpg, exhaust tip was black. The first sign is your idle will pop up to about 1500 rpm. You could wait till it goes bad then replace it. Always carry one with you in case you're far from home too. Stay away from the FAE brand, I had a new one fail at 5,000 miles.
 

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Discussion Starter · #5 ·
I just went through this O2 sensor deal onm my 2002 KRS recently. My original sensor lasted 110,000 miles. Fuel mileage went down to 20mpg, exhaust tip was black. The first sign is your idle will pop up to about 1500 rpm. You could wait till it goes bad then replace it. Always carry one with you in case you're far from home too. Stay away from the FAE brand, I had a new one fail at 5,000 miles.
20mph, that is a noticeable drop. I already have another on a spare exhaust, maybe I'll take that out and put it in my 'travel' kit.
 

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20mph, that is a noticeable drop. I already have another on a spare exhaust, maybe I'll take that out and put it in my 'travel' kit.
Oh Yeah, it was brutal. I was on my way fishing in the mountains and notice I was almost out of gas on a 90mi trip. I had to fill up before I got to the stream the fill up again halfway home. I could watch my fuel gauge needles drop as I rode....... you think I was driving an Expedition hauling a boat. If you carry one be sure you can do the repair on the road, believe it takes a 22mm open end/box wrench. The connector is up under the seat, you'll need nips to cut the zip ties too. You will need to drop the exhaust mount at the back and maybe loosen the header stud nuts also meaning you'll have to drop the belly pan. The header nuts are 12mm w/6-8" extension to hit them all. I recommend doing this at home on a trial bases to get familiar with it and it will also let the sensor be easier to take off later. Put some anti-seize on the threads when reinstalling will help too.
 

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Discussion Starter · #7 ·
Oh Yeah, it was brutal. I was on my way fishing in the mountains and notice I was almost out of gas on a 90mi trip. I had to fill up before I got to the stream the fill up again halfway home. I could watch my fuel gauge needles drop as I rode....... you think I was driving an Expedition hauling a boat. If you carry one be sure you can do the repair on the road, believe it takes a 22mm open end/box wrench. The connector is up under the seat, you'll need nips to cut the zip ties too. You will need to drop the exhaust mount at the back and maybe loosen the header stud nuts also meaning you'll have to drop the belly pan. The header nuts are 12mm w/6-8" extension to hit them all. I recommend doing this at home on a trial bases to get familiar with it and it will also let the sensor be easier to take off later. Put some anti-seize on the threads when reinstalling will help too.
That's a tough job for the side of the road. Maybe before I consider a long trip, I'll change my 98k old one for a brand new one and then put my second hand spare one (done very low mileage) in the bag. At least if it does go (unlikely), I can find a place to do the work then. Actually, thinking about it, it is very unlikely to break if I fit a new one, so I'll just do that instead. Othewise you end up taking a spare bike in your box :)
 
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