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What is the average life of an Oxy sensor before one would expect problems?
 

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Life of 02 sensor?

aa3jy said:
What is the average life of an Oxy sensor before one would expect problems?
Depends on driving style, would guess ballpark of about 75K mi. on average (mixed city\hwy), maybe higher if mostly touring miles at higher speeds using normal quality gas.
 

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After getting some strange readings on the GT1, my dealer swapped out my o2 sensor on my K1200LT at the 72,000 mile service. It was the first time it was changed. The mechanic did tell me that if you are running an after-market pipe (like a staintune that I had on my '02 RS), chip (like the RW chip on my '02), or device like a powercommander, it might foul up the o2 sensor sooner.
 

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The only thing that might cause early failure, is if the cat was removed, which is why this particular sensor is fitted post CAT. There are special sensors made for pre-cat fitting but not for our simple ECU's. 75K miles is the claimed life for current replacements, but if you're doing regular short commutes and cold starts, that comes down as the cat is not effective until hot.

For the important job they do, I think I'd change a sensor at 30-40K, for piece of mind and just to make sure it's not siezed in the muffler. They aren't expensive when considering gas mileage costs and a small gas tank.



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aa3jy said:
What is the average life of an Oxy sensor before one would expect problems?
On a car, you can expect at least 100,000 miles before it degrades to a point where the engine management system cannot "read" it. Of course, they tell you to replace it much sooner than that, but that is just a blanket statement.

The most common type of O2 sensor (the Zirconium Oxide type) can easily be tested using a standard digital voltmeter.

First, you need to know whether the sensor is a simple type with a single wire, or a "3-wire" type with an integrated heated. If the latter, you need you determine which wire is the one leading to the actual sensor (not the heater). Tap off the signal wire so it is externally available (e.g. stick a pin through the insulation and into the copper wire), then plug the sensor back into the system.

Start the vehicle, and drive it until it is thoroughly warmed up. Connect the (+) lead of the digital Voltmeter (DVM) to the sensor's signal wire "tap" as above, and the (-) lead to a solid engine ground.

Now, watch the meter. What you SHOULD see at idle is the digits jumping around with a low number occasionally reading near zero (less than 0.2V), and a high number above 0.5V (preferably occasionally reaching 0.8 to 0.9V).

This means that it is working acceptably well.

This type of sensor is in effect a miniature fuel cell. It is exposed (on one side) to the atmosphere, and (on the other side) to the exhaust. When there is O2 present on one side and not the other (i.e. when the exhaust contains no residual O2), a new sensor generates about 0.9 Volts. When there is even a small amount of O2 in the exhaust (and therefore the senor "sees" O2 on BOTH side), it generates NO voltage at all.

In operation, the system is constantly dithering between slightly lean (a little residual O2 in the exhaust) and slightly rich (no O2). As soon as the sensor detects a slightly rich condition, it commands the system to make it slightly more lean, which then results in the system detecting a alightly lean condition and commanding the system to make it a little richer.... and so on. The system constantly dithers between very slightly lean and very slightly rich.

Note that the actual VALUE of the voltage generates is irrelivant. All that matters is that the system can detect a voltage has been generated (meaning a rich condition is detected) OR no voltage has been generated (meaning a lean condition has been detected).

As the sensor wears out, it generates less and less output voltage when the exhaust contains no residual O2 the "high" number will get less and less. Eventually, as the thing wears out, the voltage generated as a result of a rich condition is not high enough to be able to be interpreted properly, and at that point the sensor is useless.

By actually testing the sensor like this, you only need to replace it when it ACTUALLY NEEDS REPLACEMENT, which can be as much as 2 to 3 times less often than what the manufacurer states.

Bob.
 

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voxmagna said:
The only thing that might cause early failure, is if the cat was removed, which is why this particular sensor is fitted post CAT. There are special sensors made for pre-cat fitting but not for our simple ECU's. 75K miles is the claimed life for current replacements, but if you're doing regular short commutes and cold starts, that comes down as the cat is not effective until hot.
Actually, the original Zirconium Oxide type sensor invented by Bosch which was first used before 1980, and is still in use on many car models, was placed before the cat in nearly every car with one, for years and years. My old BMW 320i (with 3-way cat) had such a sensor placed before the cat. Both my 1988 and 1990 Jettas have the same. It wasn't until relatively recently that sensors began to be placed after the cat. Certainly, there is nothing special about a sensor placed between the engine and the cat.

Bob.
 

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RFWILSON said:
Actually, the original Zirconium Oxide type sensor invented by Bosch which was first used before 1980, and is still in use on many car models, was placed before the cat in nearly every car with one, for years and years. My old BMW 320i (with 3-way cat) had such a sensor placed before the cat. Both my 1988 and 1990 Jettas have the same. It wasn't until relatively recently that sensors began to be placed after the cat. Certainly, there is nothing special about a sensor placed between the engine and the cat.

Bob.


Roger that!

and the write up on testing is valuable info, thanks.

BTW, the O2 sensor on a K1200RS is located just ahead of the (2)cat. cans in the chamber under gearbox.
 

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MikeK said:
Roger that!

and the write up on testing is valuable info, thanks.

BTW, the O2 sensor on a K1200RS is located just ahead of the (2)cat. cans in the chamber under gearbox.
Glad it was of interest. Also, the verification that the O2 sensor in the K1200S is placed before the cat(s) makes sense. In every car I am aware of (which is not to say I have seen every car!) that has a sensor after the cat, there is also a "primary" sensor ahead of the cat. The sensor after the cat is sort of an "auxiliary" sensor that is just used to fine tune the mixture.

Bob.
 

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A replacement O2 sensor is $109 here . Is that a good price? I've bought plugs there before at $4.95 ea.
 

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Brent,

I don't have any experience with that source for an o2 sensor, but Chicago BMW has the OEM part for $148.

I went to http://www.realoem.com and took a shot at looking up part numbers. You can get a more definitive shot at the part number if you provide RealOEM with the last 7 digits of your VIN to pin down the exact part number you need.

11781341022 - listed as the OEM part on the 1998-2001 K1200RS (doesn't come up on BMW of Chicago's website)
11787671756 - listed as the OEM part on the 2002-2004 K1200RS/GT (shows up for $146)

It appears that the new part superceded the old part.

http://www.chicagobmwmotorcycles.com/
 

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If you can find the bosch part number you can probably find it cheaper. There are a few online retailers that specialize in oxygen sensors. I took the o2 sensors out of my wife's BMW 740 and searched on the actual bosch part number and got them for less than half the dealer price. --Jerry
 

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Stephejl said:
If you can find the bosch part number you can probably find it cheaper. There are a few online retailers that specialize in oxygen sensors. I took the o2 sensors out of my wife's BMW 740 and searched on the actual bosch part number and got them for less than half the dealer price. --Jerry
I did the same years ago for the O2 sensor in my old 320i. One must remember that car and bike manufacturers are not in the catalytic converter and engine management business. they buy from companies like Eberspächer, Leistritz, and Ernst (for cats), and Bosch (engine management and sensors), so buy it direct and save a ton of money. Bosch's part number will be stamped right on the O2 sensor.

Bob.
 

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eljeffe said:
Brent,

I don't have any experience with that source for an o2 sensor, but Chicago BMW has the OEM part for $148.

I went to http://www.realoem.com and took a shot at looking up part numbers. You can get a more definitive shot at the part number if you provide RealOEM with the last 7 digits of your VIN to pin down the exact part number you need.

11781341022 - listed as the OEM part on the 1998-2001 K1200RS (doesn't come up on BMW of Chicago's website)
11787671756 - listed as the OEM part on the 2002-2004 K1200RS/GT (shows up for $146)

It appears that the new part superceded the old part.

http://www.chicagobmwmotorcycles.com/

This is gonna hurt, but when I was working with the German company Eberspächer (Europe's largest manufacturer of cats and mufflers), it was well known that the typical O2 sensor cost less than $10 to make! So let that be a guide to what is a "good" price.

The lesson? Buy from a Bosch dealer. Never buy this sort of thing from the OEM!

Bob.
 

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Yes, I trotted along to my friendly Bosch dealer with the Bosch part number. Immediately with no prompting they will tell you it's for a BMW K1200 on 8 weeks back order or something worse. They told me the wait time was for their next production run from their plant somewhere in Europe. I got the same story from 2 other Bosch dealers. I know these dealers normally give a promise of 2 days and usually come good. So I started smelling rats! Like they manufacture a production run solely for BMW and its dealer network.

That's when you you find out that the connnectors are BMW motorcycle type specific. I dived in for a Bosch Universal sensor (latest series, higher life claimed over pre-1999). It was listed alongside the oem and came with an enormous range of plastic mecanno kit connectors and adaptors, but I didn't like the bulky size. I used crimp connectors and heatshrink for the splice, have had no problems and better fuel consumption. Cages seem to have more standardised connectors, so finding alternatives is much easier. I paid less than $100 all up with local taxes. In UK the BMW dealers wanted $200 for the oem part. At $148 I'd definitely go for the oem, but my options were limited.

Whether the Bosch Universal is any different from the oem is for somebody to prove, but I'm happy.



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voxmagna said:
Whether the Bosch Universal is any different from the oem is for somebody to prove, but I'm happy.
Good move. The only difference between what you got and the OEM part is indeed just the connector. Bosch makes relatively few different types of basic O2 sensors. After all, why would they? They also make the Motronic engine management systems that the O2 sensor plugs into. So it's not like Bosch would have to make a special sensor because each vehicle has some special requirements... Bosch makes the parts on both ends of the wire!

Unfortunately, it is the vehicle manufacturers that make the connecting wires, so using special connecltrs is just their way of trying to ensure you buy their overpriced sensors from them.

...and as for overpriced electronics, I took the engine management system from my Jetta apart a while back just for fun. In total, there was less than $40 worth of components in there (recognized every single part used, except for one custom chip). The cost to replace the device from VW? $800 - $900!!

If it's electronic, then it is magic, and if it's magic, then it MUST be expensive!

Bob.
 

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Right on Bob! If I had a scrap ECU I'd be trying to read the firmware code and disassemble it. I suppose we must allow some costs for them to develop the firmware, but when that Marque gets put on the box, wow do we pay for it.

These days it's the firmware code that screws you, not the discretes. I had a perfectly good airbag unit I accidentally put a fault on. But it wrote a self destruct code 'I am dead never to be used again' into its non-volatile memory that couldn't be erased by the shop. I have never seen so much circuit technology as was in this box.

Apparently auto ECUs and sensors may be sold in future with an embedded table identifying all the electronic sensor parts, each with their own serial signature number. Only dealers will be able to update the table after they sold you or fitted their new replacement. The ECU will only work with serials it knows about. Getting old good parts off a scrapper will be history. But tracing a stolen vehicle may be easier.

Did you know that cage ECU's often contain tables with engine/chassis and registration details? When you go buy a used cage, having an OBD11 reader and knowing how to use it could be very useful.

If your vehicle gets in a fatal crash, did you know they often do diags readout? This can tell them about logged faults and what happened to airbags etc on impact. Scary stuff isn't it? I replaced an information readout panel in a GM vehicle. The panel module and ECU had to be re-programmed so the electronic trip odometer would give the right readings for the axle and tire combination. Fortunately at the moment, KRS ECU's are expensive, but relatively simple.



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voxmagna said:
Right on Bob! If I had a scrap ECU I'd be trying to read the firmware code and disassemble it. I suppose we must allow some costs for them to develop the firmware, but when that Marque gets put on the box, wow do we pay for it.
But it's not just firmware that screws you. Remember back when turn signal relays were purely electromechanical? They had a bimetal strip and a little heater coil inside.

Well, that was too expensive for manufactuters, so at some point they switched to an electronic version because it was cheaper.

Well, not to replace it is isn't! One price I saw once for the VW replacement (electronic) signal module was close to $100!! Not bad for a device that has less than $1.00 worth of parts inside!

The irony of this is that the local aftermarket suppler sells a plug in replacement that is (surprise!) the old-fashioned bimetal type for about $12.00!!

Did you know that cage ECU's often contain tables with engine/chassis and registration details? When you go buy a used cage, having an OBD11 reader and knowing how to use it could be very useful.
Absolutely! We have a pollution inspection facility here that does a dyno test of the car while testing for emissions. When they are finished that, they read the vehicle's OBD11 module to look for previous trouble codes.

While taking my car through, the guy noted that I had no previous trouble codes. Just to get his goat, I told him that this was because I erased them before I came! Boy, did he get his knickers in a knot! I just told him that what my car had done in the past was none of his damn business, and that all that mattered was if my car passed the test NOW, not if it may or may not have had some problem in the past. After much grumbling, he had no choice but to issue me a "pass".

Bob.
 

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I can see that all happening here soon as well. If it's an electronic turn signal unit, I just open up the can and fix it. But once they put in firmware and microcode chips it's just a bridge to far. On some simple items I have taken a pragmatic approach, ditched the unreliable fancy electronics and swapped the part out for something simple and reliable.

Comparing the old turn signal units with a solid state part requires a more complex design. The old heated wire unit told you when a bulb failed - less heat on the wire so it stuck on or flashed slow, also when you hit the turn switch the indicator lit 'on' first.

Some electronic aftermarket units fail on the last point, which is a requirement here, as is the indication of lamp failure. The upshot is that the electronic unit is more complex. although its flash rate may be more accurate.

I bet they were looking for the trouble codes to frighten you into having more work done! You were right to argue your rights. We just have to try keeping ahead of the game.



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voxmagna said:
I can see that all happening here soon as well. If it's an electronic turn signal unit, I just open up the can and fix it.
Exactly, I have even fixed a fuel injection system's controller some years ago. The problem was pretty obvious, namely that the power transistor driving the injectors was blown. I just replaced with a similar NPN power transistor (50 cents) and saved myself $800.

Comparing the old turn signal units with a solid state part requires a more complex design. The old heated wire unit told you when a bulb failed - less heat on the wire so it stuck on or flashed slow, also when you hit the turn switch the indicator lit 'on' first.
What's funny about this, is that the design "deficiency" where the old bimetal signal relay's flash rate was dependent on the load (as you mention), became a "feature".

When a bulb burned out, the flash rate changed dramatically. At some point, people started to realize this unintended "problem" was a good warning that a lamp was burned out.

So when electronic flashers were first introduced, they had to actually ADD a current sensing circuit (typically a reed switch with a coil around it), at increased expense, and a second set of timing components. When the current to the lamps dropped below a certain threshold, the second riming circuit kicked in to flash the lights faster to warn a bulb was burned out.

In short, they had to add cost and complexity to get the electronic flasher to do something the mechanical ones did naturally! Ironic, huh?

Bob.
 

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Right on Bob, but why are people so obsessed with paying more because it's electronic? Over here they want us to be energy efficient, go out and buy lots of replacement flourescent light bulbs.

The first generation ones albeit a bit large, made by Philips, ran for 5-10K hours. Then they told us the wound chokes were only 90% efficient and this was bad news, so they brought out all electronic switching models. They cost five times the cost of a tungsten bulb, with a claimed life of 10,000 hours and many calculations on how much money you can save running them.

The real truth is the manufacturers went electronic to cut costs (replace the expensive reliable wound choke) and to get a smaller unit. Unfortunately, whilst the tube might last 10,000 hours I've never had the voltage spike prone electronic versions last more than 2000 hours as it's now the electronics that fail before the tube. Then there's new emc issues they have to deal with. Cost of owning and replacing these lamps is far greater than before. I don't know where the energy efficiency comes from in real terms .

When somebody tells me their latest model is more energy or fuel efficient etc, I always try to look at these things in terms of real cost of ownership - there always seems to be a hidden cost somewhere.



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