P.S. Oh ye of little faith!
Thank you
As a mechanic, I can tell you that it is HIGHLY unusual for a vehicle manufacturer to recommend oxygen sensor replacement at set intervals . . . nowadays
We have GM, Ford and some Toyotas in our fleet, and those vehicles do NOT have a set replacement interval. Also, when I was working at the Benz dealership, only the “classic” cars had a set replacement interval.
I suppose that makes BMW proactive
I view this as a personal preference issue, much like when people change the oil in their cars. I tested my Mobil-1 EP at 8800 miles, several years ago, almost all highway driving, and it was still good. So, now I change my oil at around 8,000 miles. Yet, others feel they must change it at 3,000 miles, like they did decades ago.
Since I am several hours from a Toyota dealer, and any parts will most likely be air freighted in, I tend to do what the military calls high-rel maintenance. Docnick was the only one who understood this the first time I mentioned it, because he worked on that program.
In a professional high-rel program, manufacturers engineers examine every component in a military vehicle or aircraft, and determine the approximate range of use which will most likely result in the first failure. All statistical, of course, based on past observations.
Somewhat before that usage point, they replace or overhaul the component to avoid any unexpected failure, or at least create a very low probability of unexpected failure.
In the case of O2 sensors, they do tend to show some failures near 100,000 miles. If you live down the street from a parts source for O2 sensors for you car, and don’t take long trips, don’t worry about it until you have a failure.
If you are quite a ways from a parts source, or take long trips, replace them every 100,000 miles and forget about it.
In the same sense, some of us replace our battery every five years even if it tests okay. I have always done that, but a couple years ago, an expensive US battery failed here in Mexico when only 2 years old. I put in an LTH from a local store, fortunately I was not in the middle of a long trip or anything.
The first time I mentioned here high-rel some wise guy asked why I didn’t replace the motor or transmission every so often. The answer is, if there was a known failure rate, then I would, based on the expected time of failure.
My first high rel posting was on light bulbs. And, most folks said they seldom ever fail. That was at 75,000 miles. So, I didn’t replace them. A few months later, I forget, I think it was 84,000 miles, I came in from a long trip and the high stop bulb was burned out. So, now I replace that bulb every 60,000 miles or so.
There is always a trade-off on these issues. When you take long trips, and can’t afford failures on the highway, you do one thing. If you drive mostly around your own home, you can do another. If you drive into another nations, you also need a different plan. If you live in a very hot or very cold environment where a failure can actually be life threatening, you also should have a different plan. And, the car owner is the one who should try to be informed and make that decision, partly just on how he feels about it.
I must wonder on that BMW if the engineers made that decision based on what an owner of an expensive car like that would think if he has problems with fuel efficiency or operation, when a simple planned replacement within the range of first failure would eliminate it. Sure sounds right to me.
Over the years several vehicles, domestic and imported, have incorporated time/mileage counters to predict O2 failure. A warning light would indicate that the sensor needed testing and possibly replacing. To determine whether the cat or the sensor is failing an oscilloscope can show a very clear picture of the sensor output and comparing the front and rear sensor outputs while introducing extremely lean and rich mixtures will indicate what is failing.
If something REALLY needs attention, you will know about it soon enough…Once a drivability or engine performance problem is detected, true, it’s time to get it fixed, just like in cars without CEL’s…But to spend $1200 to turn off an emissions light in a state with no emissions testing, well, that’s up to you…