Do oxygen sensors eventually all fail?

Maintenance/Repairs
21

My opinion is that it depends. Many O2 failures are caused by other faults; coolant leakage into the cylinders, chronic misfires, partially clogged converters, running excessively rich, etc.

Many O2s last the life of the vehicle. I’ve never had to buy an O2 for any of my cars or family members cars except one time and that was when a wrench slipped while doing some maintenance and the wrench hit and cracked an O2 on my old Mercury. Since I was about to make a trip to the local Pull-a-Part for a pair of heads for a custom project I simply picked up a used one for 5 bucks. It worked fine.

SAAB was one of the first car makers to use O2 sensors in their Lamda systems (back in '77) and their recommendation at first was to replace them every 15k miles. At 400 dollars a pop, in 77 dollars, this did not go over very well with SAAB owners. They revised it to 30k mile intervals (more complaining), revised this to 60k miles, and eventually said only to check them at 60k miles and replace if necessary.

22

WHAT are oxygen sensors and how do they operate? http://en.wikipedia.org/wiki/Oxygen_sensor
And, why can’t you just carry spares if you fear failure?
Predicting failure rate on a large number is possible; for four, not.

23

As posted by others, O2 sensors last a long time, and there is no “failure development curve” ( a technical term for wear curve)for such an itme. Toyota uses statistical quality control that allows about one defective sensor in 344,000 (Six Sigma), and has specified a predetermined life, such as 200,000 miles. The inherent safety margin will allow 300,000 miles most likely. Don’t assume that European, American or most Korean manufacturers practice this level of quality.

Toyota knows US drivers will actully wear out this car, whereas in Japan, after 10 years and driving a maximum total of 100,000 miles this car would normally be scrapped!!

If your car was an aircraft, you would likely proactively replace these sensors at 200,000 miles, to ensure continued peformance. Since you live and work in the remote areas, this makes a great deal of sense.

I worked in Saudi Arabia where many vehicles go out into the remote desert. The vehicles I rode in had ALL their hoses and drive belts replaced every 2 years. Hard experience here dictated a proactive and failure prevention mode of maintenance.

24

From Docnick: Don’t assume that European, American or most Korean manufacturers practice this level of quality.

Is this conjecture? How can you know this?

25

Yes, the question is not IF, but WHEN.
Various factors influence the “when”, Engine exhaust temp, contamination, etc.

and if the O2 part of the sensor does not fail the heater may fail, just like a lightbulb.

Pb and Silicone will “kill” a sensor pretty fast, depending on concentration. All gas contains Pb, even if @ the PPM level, so failure is guarenteed… eventually.

Silocone gasket adhesive is another common killer. commonly used for sealing valve and oil pan covers, so be warned.

there are pretty much 3 types of sensor, the common Bosch, Wide Band, also Bosch and a japanese type of oxygen Dependent resistor.

Here is some information on the Bosch type;

http://wbo2.com/lsu/lsu4.htm

Hard to get info on the resistor type, Titania type, older Nissans used them. essentially instead of generating a voltage, you fed them a fixed voltage or current and measured the other.

I don’t know what kills the Ti type… probably the same.

In either case the car will not stop dead (unless you have a short in the heater and it blows fuses).
the life of a sensor is anywhere from a few thousand miles (see contamiants) to infinity, (however most get slow to respond at about 120Kmls).
It’s a bit like, if you never switched off a light bulb it may last forever,
see; http://www.centennialbulb.org/

26

That light bulb has a carbon filament. Modern light bulbs use tungsten and they have a definite wear rate. Modern bulbs last longer if left on because they are not subjected to the the electrical and mechanical shock of being turned on with the filament cold. Ever notice that they almost always fail when turned on?

Is it possible to buy leaded gas in Mexico? That would be a tragic mistake for the O2 sensors.

They seldom fail catastrophically unless polluted or mechanically damaged. Their normal failure mode is gradual and can be indicated by a slow deline in mpg. They tend to get lazy and slow to respond so the control loop has hysteresis it shouldn’t have normally.

Even though the narrow band sensors are more expensive, I would consider it cheap insurance to have a couple of them on hand, if nothing more than the convenience due to the difficulty in getting them.

27

My 1988 Accord LXi has 217k miles and the original O2 sensors and converter. It gets the same MPG as when it was young and passes emissions (IM240) by a wide margin. All I’ve done is keep up the maintenance and drive gently.

28

Six Sigma quality control is slowly finding its way into the car industry. Honda was the first, followed by Toyota. US manufacturers used to accept 1 bad part in 10,000 rather than 1 in 344,000 used for Six Sigma. British Lucas electricals used to have a 30% failure rate at the production line, hence the poor perfromance of British cars using them. When Ford bought Jaguar they immediately cracked the whip on their suppliers, and parts quality went up.

When Japanese car plants are established in North America, many established parts suppliers try to qualify for parts contracts. Many do not make it because they can’t meet the design life and quality standards.

Having said that, the situation is improving rapidly for US manufacturers and the quality/durability is closing in on the Japanese. Similarly, Hyundai of Korea is rapidly improving its reliability. European manufacturers still have a durability and quality control problem with outside supplied components, especially electronics.

The Chinese are aware of this gap, and it will take them some time to get the design and durability up to what North American buyers demand. If you want first hand experience with Chinese-designed consumer product quality, buy a Haier refrigrator, and let us know how long it lasts. Chinese made electronics, on the other hand, are designed elsewhere and the quality control is either Japanese, or American.

29

Agree that O2 sensors more often fail from being polluted that from wearout. A few years ago the car manufacturers rejected a gasoline anti-knock additive (to replace MTBE) because, although it was very effective, it tended to coat the O2 and other sensors. There is wide availability of lead-free gas in Mexico, as I recall, so you don’t need to tank leaded gas.

Keeping the engine in tune and sqeaky clean will do a lot to maximize sensor life.

30

Agree that if you keep your car well maintained, the O2 sensors are pretty trouble-free. I’ve only ever replaced one, on a 1988 Caprice V8. It was part of the tuneup, and the mechanic said I needed it to meet the emission tests.

31

Agree that if you keep your car well maintained, the O2 sensors are pretty trouble-free

That’s a good point. And I do keep my vehicles very well maintained.

32

if you think like that,why dont you replace the catalysts on the exhaust?or replace the fuel pump?or replace the head gasket? just in case they may fail???what im trying to say is you should wait and see!it may never fail,but if it does you can still use the car until another one is available.

33

Your poll has been for (HEATED) OXYGEN SENSOR longevity. Your vehicle has only ONE (heated) oxygen sensor…and it’s located after the catalytic converter. The 2002 Toyota Sienna has two AIR FUEL RATIO SENSORS in front of the catalytic converter. The data, for (heated) oxygen sensors, is not, necessarily, pertinent to A/F Ratio Sensors.

34

I’ve had a couple of O2 sensors fail. They were $35 at Autozone. The Autozone dudes told me which one was bad. Sold me a sensor, loaned me a special socket to change it out and in about 15 minutes I was done. None of that $300 stuff for me.
That was on a Ford Expedition with about 101k miles.
Even with a bad sensor it will run, shouldnt be a reason to tow it.
From what I’ve read, the worst thing for a sensor is Glycol contamination, like antifreeze, but so is crappy gas( maybe like in Mexico? I’m not sure about that).
I talked with our mechanics at where I work and we have a fleet of 100 Chevy Silverados and they have never…that’s never…had to replace an O2 sensor.
Now we get rid of trucks at 125k…maybe thats the reason.
Good luck…
Paul

35

Let’s see, coil pak, ignition module, crankshaft position sensor, Fuel pump, fuel pump relay, MAF sensor, and MAP sensor can all go, and keep the engine from starting. Then there are wheel bearings, brake master cylinder, brake calipers and cylinders that will render the van very unsafe, and virtually undriveable. And if yo have an Automatic transmission, with this many miles, it can let go at any time, and leave you totally stranded. Even if you changed the fluid every 30,000 or less. And, they can give out with no warning.

36

I think it depends on your car. My 89 Tracer still has the factory O2 sensor with 377k. My 95 Tracer needed a new one at 55k. Almost everyone I know that owns and Escort/Tracer of 91 and newer vintage has replaced at least one. Also an o2 sensor will generally give you a check engine light and cause the car to run rough or get poor gas mileage. It is unlikely to strand you. Of course that is based on the 6 Escorts and Tracers I own or have owned. I am not that familiar with other makes.

37

Just talking about high-rel maintenance on the aircraft engine pre-heating thread, I realized I had not updated this posting. Even when advice is useless, I really appreciate a fellow human taking time to respond to my request for information. No one is obliged to do it. Thanks to all.

There was some good information there. I had to choose which advice was important to my circumstances, which is an attempt to replace with a plan, parts that do fail at times, but without warning. I chose to take the advice that the sensors eventually fail, and decided to have the new ones put on. With nearly 150,000 miles I do not think they will need to be replaced again.

It was a good thing I had them replaced instead of just buying the parts and taking them with me The hardware on the rear sensor was shot and they had to order new, which would have been a wait of many days in Mexico.

I think it was Docnick who best understood high rel maintenance, with his tale of replacing parts on vehicles used in the desert every two years. Someone else wondered why I didn’t just start replacing parts en masse, even things like the head gaskets, which is sort of ridiculous on a car which does not have a significant failure rate on head gaskets. The idea is to find out which parts fail and when. Then, with a reasonable plan, replace parts which are:

  1. Most likely to fail in the near future, even if you are not sure exactly when, and if no other formula exists, when the car has reached its 50% point, if it is likely to fail at all. I do not expect to drive this car more than 300,000 miles, so now is the time.

  2. Likely to either disable the car, or cause damage if it is driven. I found plenty of mechanics who said driving with bad sensors can wipe out the catalytic converter. Some posters seemed to think I could drive that car hundreds of miles with bad sensors.

If I had any reason to believe there is a significant failure rate on Toyota head gaskets, yes, I would have the suckers replaced per plan. But, I have no such information.

If I had any reason to think the transmission would fail in the near future, I’d have it rebuilt as well. I know it can happen, but I believe it is rare when the ATF is changed often. So, on that, I am not having it rebuilt.

By the way, perhaps there is only one heated sensor, the one behind the cat converter as someone said but my first sensor failed some time ago, and the failure was THE HEATER BURNED OUT. CEL came on, and that was the code stored. It was the a/f sensor I forget which bank.

I also replace my batteries at 5 years, no matter how good it might be. This is also about the halfway point on a car. I used to wait until they broke, miss work and have to work on that car at 20 below zero after paying top dollar for a battery. This was the first thing I learned to replace with a plan.

I also have a new policy to replace all external light bulbs every 75,000 miles. When this Sienna had about that many miles, I asked about that, since cops are using bad bulbs as an excuse to harass people into letting them search their cars, like common criminals. I got some really bad advice here, including positive statements that bulbs don’t fail any more. So, I decided not to bother. At 85,000 miles the high-stop light went, I caught it before the cops did, so I learned to replace all bulbs on a schedule. A California attorney posted on the Sienna Club that in California the cops are now writing MOVING VIOLATIONS for bad bulbs. It is time to shift gears on the old traditional wait till it breaks concept.

I used to do it the way many of you seem to recommend. Wait until it breaks. If there is an Autozone just down the street, as is the case for many of you, this may be a valid choice. Just as Docnick’s desert vehicles could not afford to do this, neither can someone living far from parts/service. This concept is so simple I am stunned that there are so many people who can’t grasp it. Thanks, Docnick, good job!

If one does this sort of thing for a while, you learn you can drive a car a long ways with fewer failures, and in the end the cost of high-rel maintenance is small compared to what most people do which is let this stuff go, then throw up their hands and get a new car, which would cover a lot of parts and repairs.

I understand eventually I am going to miss something. Maybe my head gasket will fail, heh, heh. Such is life. All we can do is our best.

38

As long as you are happy with your decisions, that’s great.
No one said not to perform any preventive maintenance. The problem is knowing, or guessing, what parts will fail next, and when. For one mechanic to not be in agreement with another mechanic isn’t something which reduces or negates either’s abilities, or knowledge.

39

Consider this. Yours have lasted a long time, a replacement may only last a week.

40

I have been considering replacing the O2 sensor on my '95 Chevy S-10 just as preventative maintenance. Truck has 175,000 miles and as far as I know, the original sensor is still working. I just replaced the the whole exhaust including the catalytic converter. The old cat was still working but the hangers had broken off.

How hard is it to remove the old sensor? I know I need a special socket to remove it. I’m worried about it breaking off due to the age and mileage, it must be stuck on there pretty good by now. Should I bother replacing it, or just leave well enough alone? I don’t mind spending for a new one and installing it, but I don’t want to run into any problems with the removal.