If the O2 sensor is going bad or bad will the computer always show a code for it?

~Josh~

 

O2 sensors don't go bad. They only get dirty.

The way an 02 works.There is nothing to break, except the lead wires. It only gets dirty.

Depends on how hot you get it.
It can work one day and then set off a code the other.

One day in light normal slow traffic it could come on.

Take a trip at 65-70 for an hr the next and it gets hot enough to self clean and the light goes out.

Mom Subaru did that for a bit.
After I used some fuel cleaner in it.

I just had to drive it every other day for a week or so, romp on it good and get the O2 hot/cleaned off. After a week and a new tank of gas. The light stayed off for good.

 

[QUOTE]Originally posted by Gumby
O2 sensors don't go bad. They only get dirty.

...amazing! This must be the only part in the history of automobiles that does not wear out! I did not realize O2 sensors lasted forever.

EDIT: To answer your question, no the computer will not necessarily know if the O2 is bad. For our cars they are cheap to replace, but they do not have to be replaced as often as the auto parts stores would like you to believe. If you are having some running problems I would not suggest you throw money at it until you have attempted to thoroughly diagnose the problem.

 

[QUOTE]Originally posted by Aaron R.

Quote:

Originally posted by Gumby
O2 sensors don't go bad. They only get dirty.

...amazing! This must be the only part in the history of automobiles that does not wear out! I did not realize O2 sensors lasted forever.

It only gets dirty. It could last forever as long as the wire leads never got damaged. And if you could take them apart and clean them, it would.

But its why you can buy $80 ones with self cleaning tips.

Which is sort of lame. They just use material that doesn't attract dirt as much. It will eventually get dirty and fail.

There are not parts to wear out or fail in an O2, they only get dirty.

 

Funny, as a Smog Tech, I have never heard of this. I have taken ASE classes and they tell you that they get old and stop working. If you understood how an O2 sensor worked, then you wouldn't have said that...

Plus the fact that there is NO WAY to clean an O2. Wait, I'm lying, if it's carboned up from running rich all the time, you MIGHT bring it back to life by some high revs after fixing the rich condition, but if you spray it with something, it screws up the sensor.

There may be no parts to wear out, but there is a coating of chemicals that eventually wears out. It just stops working. There's nothing you can do about it. It's like a catalytic converter, they DO wear out, but there expected life span is like 10 years...as long as there is no other problem upstream from it. You get a misfire or something and it drasticly shortens the lifespan. O2's are 30,000 mi sensors, that's it.

Anyway, no, you will not always get a code for a bad O2. The only way to test one acuratly is to use a DSO and a propane enrichment tool. If you're in doubt, just replace it. They're fairly cheap and it won't hurt if it's in question.

 

The chemical reaction between the oxygen in the exhaust gasses and the coating of the sensor at operating temperature will slowly eat (oxidize) the coating over time... there's no way to get around that. You can't sit there and produce .5-1.0v of electricity from a chemical reaction without sacrificing something in the process (otherwise cold fusion might work). Granted, however, most O2 sensors in thirdgens die a horrible death long before their coating is oxidized beyond limits thanks to foreign substances.

 

Damn you Techsmurf! You beat me to it