How do i check/know if I need a knew O2 sensor?

 

A. If the sensor truly is defective and just plain isn't working, it will throw a computer trouble code, and your "check engine" light will come on.

B. GM does recommend regular replacement of the sensor....someone correct me, but is it every 30,000 miles?

Many people say they've enjoyed better fuel economy after replacing the sensor...I'm still not sure yet with my other GM car.

So the answer is, if your check engine light is off, your sensor works. But if you bought the car used and you don't know how old the sensor is, you might want to replace it. They're cheap, but can be very frustrating to work on.

 

ok, thank you

 

i think you can just do a visual inspection too. jeut take it out and if it is very black and covered in carbon, chances are good that its on its way out. i may be wrong though..because the might always be black. all i know is that mine was shot before and it was covered in carbon.

-brian

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1991 Camaro RS
GMPP 350 HO crate engine - 454 TBI, MSD ignition, SLP exhaust, everything is new
700R4 - 2,400 stall converter, vette servo, shift kit
My car's webpage - z28boy.cz28.com
President - Central New York F-Body Association
Email - z28boy@twcny.rr.com
AIM - "Z28 Boy"

 

i was actually told once on the boards that a O2 sensor never really goes bad, just gets really dirty. And you gotta clean it off. Not sure who said that too me but dont quote it.

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1991 Firebird (GT40)
-LO3 305 TBI
-5 speed
-Open Element Air Filter
-Edelbrock Tower Strut Brace
-Kenwood Excelon Headunit w/ 10 Disc Changer
-Alpine MRP-F256 Amp
-Polk EX 4x6's, DX 6x9's, and EX Tweeters
-Kicker ZR240 amp (bridged)
-Dual JL W0 12" Subs

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My page with pics and stuff, and car stereo help.
http://members.aol.com/deadtrend1/index.html

 

It really depends on the state of tunne the engine is in. I've had one last almost 150K miles, but I'm a major tune up freak.
One tank of leaded gas, can ruin one.
There are too many variable for specific answers.
For the price, if in doubt replace it and keep the old one for a working spare.
Better yet update to a heated version.

 

I just replaced mine today with a Bosch one. It was only like $25 and I was/am getting 11mpg; so I hope this helps. I put it in using a socket made for O2 sensors and it took maybe 5 minutes for the whole swap.

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Brady
"I see myself as a huge fiery comet, a shooting star. Everyone stops, points up and gasps "Oh look at that!" Then- whoosh, and I'm gone...and they'll never see anything like it ever again... and they won't be able to forget me- ever."~Jim Morrison

 

Bosch's have a known problem with the internal ground for the sensor going back.
You can't beat AC quality.
Oh, and I had 2 Boschs back to back fail like that.

 

How is the heated version better?

 

I wouldn't think it's any better, maybe more reliable under changing exhaust gas temps. Probably more accurate because it's a stable temp, I don't know, just thinking outloud.
Anywho, my o2 sensor change took a total of 1 minute after I got the car jacked for other odd jobs. I took a cresent wrench and it took little effort to remove.

 

To my knowledge, it's only necessary to use a heated O2 sensor when it's located to far down the exhaust system for the engine to provide enough heat for it to work properly. I could be wrong, but I don't think there'd be any advantage in "upgrading" to a heated O2 sensor when ours is placed so close to the heads.

Jason

 

A heated O2 sensor -might- help out slightly at startup as sensor will be heated without having to rely on exhaust gases doing it (at idle, exhaust gases could take as long as 5 minutes to heat one up to its operating temp.

 

Yep, just borrow that tool they should have at the autoshop for changin the O2 sensor and it should come right out. If its stuck, let the car idle for a little while to let the manifold heat up and it should come out a little easier (I think...). Just dont touch anything or wear high-temperature tolerant gloves if you let it warm up!

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Chuck Kulchar
1991 RS
Open Element w/K&N
3" cat and Force II cat-back

 

If you tighten O2 sensors too much, their outputs can be distorted...

 

Hey guys, i'm new at this so bare with me. Where is the o2 sensor located? My car is in my sig. Thanx! I think i need to replace it cuz my car was a one owner, but when i bought it a couple years back, it still had the original "stock" spark plugs from 1992! It was in great condition though, exept for the tune ups, so i think i need a new 02 sensor.....thanx again!

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92 Firebird 305 TBI
K&N Open Air Element
K&N Crank Case Filter
Just a begginer, soon i will advance!

 

It's in your y-pipe on the drivers side.

 

Dahulk, it's on the driver's side exhaust pipe, visible from above. It's much easier to see with the air cleaner duct removed...which is probably already gone, since you have an aftermarket air cleaner.

It's directly next to the cylinder #4 spark plug...that is, the third plug back from the front.

The sensor looks something like a spark plug, but with a regular-sized wire coming from it.

 

If you were into PROM programming, with a heated O2 sensor, you could program the computer to go into closed loop earlier, especially on hot starts.

There's also that issue of moving the sensor down past the collector so that it could read the combined gasses from both cylinder banks, rather than just the driver's side bank. In that case, a heated sensor would be a good idea to keep up quick heat-up times.

Back to the original question: if yours A)hasn't been replaced in over 30,000 miles, B)since you've bought the car, C)it's getting bad mileage, or D)you just don't know, then you should replace the sensor. They're cheap enough you can look at it like that. If they were $100+, then we would probably look closer at whether or not the sensor is bad or inaccurate. Like Grumpy said though, some will last way past 100k, and some don't make it past a bad tank of gas.

Chris: that's actually cylinder #5. Even numbered cylinders are on the passenger side. You might have been looking at the picture upside-down.

 

You answered your own statement.
It is more accurate (ie better) since it establichs a known base temperature.
Better if it allows faster closed loop (ie better mileage, not a huge amount but everything adds up).
More positive closed loop after hot restart, yep all in all just better.