O2 sensor

[AFBeefcake]

how long do the O2 sensors last and how do you know if there going bad.

[Landshark]

you'll get a check engine light when they kick, and it will show up as a trouble code. i had the CEL for a day and it went away. i may be changing out mine, too. have to go get it scanned to see what the code is. not sure about longevity, can vary. if you want to be anal and do preventative maintenance, it probably couldn't hurt to change them around 60k-80k miles.

If you have a bad one, your air:fuel gauge will read sluggish like when the car is cold.

Mike

[AFBeefcake]

the guage will never go to rich and is all ways moving between lean and stoch.
when i start the car it moves slowly up to stoch and then starts moving back and forth.

[Landshark]

Originally posted by Green1995SVX
If you have a bad one, your air:fuel gauge will read sluggish like when the car is cold.

Mike

umm...not everyone has one of these, Mike i wouldn't mind having one, but two extra gauges are enough for me - i don't want to feel like i'm driving the space shuttle

[Beav]

Let me confuse the heck outta all of ya's. The engine basically runs from info gathered by the other sensors. The O2 sensor(s) tell the computer if the final outcome is good. If the final outcome is not good the computer compensates by varying timing (providing there's no bad reports from the knock sensor(s), adjusting the pulse width at the injectors, etc. Now the problem becomes is a bad reading the result of a bad O2 sensor or is something else causing a problem beyond the computer's ability to compensate? And for those of you with OBDII models the rear O2 sensors exist only to watch the effectiveness of the catalytic convertor.

O2 sensors are typically very reliable, however they don't tolerate being subjected to abnormal enviroments very well. Silicone sealers not labeled "O2 safe" will kill them instantly, excessive oil burning, excessive fuel will cause them to melt, as will a clogged exhaust. A coolant leak can cause anti-freeze to ruin them. I strongly suspect that those prone to spray can after can of injector/carb cleaner, etc. down the engine's throat aren't doing the sensors much good either.

Then there's the 'normal wear and tear' factor. If the car has always run perfectly chances are they'll last as long as the car.

Best bet is to use a good digital DVOM meter (I wouldn't trust the in-car meter you have to report as fast as the sensor does) and backprobe the suspect sensor's connection. The info gained through a computer connection tends to be sluggish, especially for those that use generic OBDII readers.The sensors will be sluggish until warmed a bit, usually 30-40 seconds should be sufficient. Once warmed the readings should change fairly quickly, ranging from .01 - .99 volt. The readings will vary faster as the engine approaches normal operating temperature.

If your in-car gauge is accurate, it would appear to me that something else is causing a problem.

[AutoTchr]

Beav is right, you need a Good multimeter to perform the test this way. Most multimeters can't sample fast enough to keep up with the O2.

But even a good meter won't detect a lazy sensor. This is where that graphing meter or digital storage oscilliscope comes in. Bet everyone has one of those in their tool box.

[wawazat??]

I have a question. Are O2 sensors considered wear items and should they be replaced periodically? I know what Bosch wants me to do

I have never replaced the O2 sensors in mine, now at 146K. They are the originals shipped in the car from Japan. Recently, my fuel mileage has been reduced from 24-27 freeway to 21-24 freeway. The car runs beautifully. No miss at idle, smooth rev increase, but power has been down for the last couple of years. My dealership works under the "if-its not-broke....." rule, but I'm wondering if I should replace them for fuel mileage/performance?

Thanks,
Todd