Toying with the idea of Replacing Oxygen Sensor

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Quote:
What are the symptoms of a bad oxygen sensor?
Symptoms of a Bad Oxygen Sensor:

When you have a bad oxygen sensor, your vehicle will run less efficiently, it can sometimes have a poor idle, erratic jerking at steady throttle, hard starting problems, cause the check engine light to come on, and will cause high fuel consumption.


Quote:
How do you know if your oxygen sensor is bad?
Check this list to see if it's time to replace YOUR vehicle's oxygen sensors:

Sudden decrease in fuel mileage....
Flashing check engine light or malfunction indicator lamp in the vehicle?s dash board....
Failure to pass smog....
Overall poor vehicle performance; rough idling, stalling, hesitation on acceleration, etc.


2000 Buick LeSabre
My fuel mileage has been pegged at 17.1 mpg for several months now. When I first bought the car when it was only 5 years old, fuel mileage was pegged at 19.6 mpg. Some websites recommend changing the oxygen sensor every 100k. The car now has over 131k and is still on the original upstream and downstream oxygen sensors. Idle quality is not super smooth and fuel mileage is down. No scanner to check fuel trims, so if I replaced the upstream oxygen sensor, it would be based on a hunch and the above info.
 
I have picked up mileage on cars past 100k by changing the upstream sensors. Not a huge change but say 1.5-2mpg.
 
Could just be the winter fuel blend decrease in mpg you're noticing. See if the car still has the same mileage next June.
 
1) "It's always the front one" uncredited quote

2) A neighbor with a V-6 @ 135mpg had all replaced when one threw a code.
She thought her garage an honest one.

3) My front O2 sensor went out and saw a measured 20% drop in mileage.
Your's fell 13%.

CONCLUSION: I don't know.

edit: spasm, 1.5 - 2 mpg AIN'T SMALL.
 
Originally Posted By: SatinSilver
Could just be the winter fuel blend decrease in mpg you're noticing. See if the car still has the same mileage next June.


True.

Or it could be a lazy O2 sensor needing replacement.
 
Originally Posted By: Mr Nice
Originally Posted By: SatinSilver
Could just be the winter fuel blend decrease in mpg you're noticing. See if the car still has the same mileage next June.


True.

Or it could be a lazy O2 sensor needing replacement.


Or it could be dragging brakes, low tire pressure, the OP gaining weight with the holidays approaching. All sorts of things to ponder. But for $40 not a bad price for a quality part. The same NTK front 02 sensor on the Matrix runs $280. But if it was AWD the price would be around $80.
crazy.gif
 
You're from California. The best way to see if your O2 is working is to look at your SMOG test result. High CO, HC, NoX and you should just try a new O2. I think most cars are $20-30 from Rockauto these days. It is worth replacing as a preventive maintenance once in a while (i.e. every 100k or so).
 
you can test an O2 sensor with a voltmeter. A good one will dither between .2 and .9 rapidly. If it is slow to change or doesn't change , it is NG.
 
Originally Posted By: Merkava_4
spasm3 - Did your engine's idle quality smooth out too ?


No, no change, there was no idle issue for me. I just replaced them due to mileage. It was an 03 ford escape v-6 with 130k at the time.
 
I replaced 3 out of 4 in the first six months of owning my E150. At AZ's recommendation after they scanned it for me. Every couple months I'd get a CEL. They'd scan it and recommend an O2 sensor. Did some more research after the CEL came on again. Changed the isolator bolts. It's been working for a few years now. Have a feeling I didn't need to change those O2 sensors.

Replaced the downstream in the Aveo after the scan read low voltage. After that failed to fix it I found a very small crack in the exhaust right below the sensor. Replaced the exhaust pipe and everything was fine.

Replaced one in a 1990 Dodge B250 that was bad.

Ran 185K and 186K miles on two Geo metros and never a problem with the O2 sensors.

That's my experience with O2 sensors.
 
Originally Posted By: Kira
1) "It's always the front one" uncredited quote

2) A neighbor with a V-6 @ 135mpg had all replaced when one threw a code.
She thought her garage an honest one.

3) My front O2 sensor went out and saw a measured 20% drop in mileage.
Your's fell 13%.

CONCLUSION: I don't know.

edit: spasm, 1.5 - 2 mpg AIN'T SMALL.


135mpg, OTOH, is VERY small fuel consumption for a V6
 
Originally Posted By: Merkava_4

My fuel mileage has been pegged at 17.1 mpg for several months now. When I first bought the car when it was only 5 years old, fuel mileage was pegged at 19.6 mpg.


I've seen a similar drop in mileage, and have had some of the symptoms you list. Pretty sure it isn't an oxygen sensor problem, though, because I don't have one.

In my case the fuel consumption rose after cleaning the carburettor, which perhaps opened out the idle circuit. Drivability/rough running seems to have been down to air leaks.

So your symptoms are fairly non-specific.
 
Originally Posted By: simple_gifts
Based on some of your posts, you should invest in an oxygen sensor in the cabin of the vehicle

j/k.



made me laugh good!

Seriously, even a 2000 has plenty of diagnostics built in to tell if the O2 is bad, including being able to
tell if a fake sensor was installed or a "simulator" to beat smog tests.

The software tracks engine time, temp and knows if the sensor should be hot enough, 3 wire sensors have
a heater inside and a tap wire that tells the computer if the heater blows, setting a code right away among
other things!
 
Originally Posted By: andyd
you can test an O2 sensor with a voltmeter. A good one will dither between .2 and .9 rapidly. If it is slow to change or doesn't change , it is NG.


Is that the voltage going from the signal wire of the sensor to the engine computer ?
 
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