Good morning guys! Is there a way to test your O2 sensor? I don't know if it's good or bad either way but if I can possibly get a little MPG's out of a new one I might replace it. I have 87K on the original sensor if that helps...

Also, when I look on Autozone's website it lists 2 different sensors, "Befor CAT and After CAT" which one should I be getting?? I don't recall seeing 2 under there but I haven't been under my truck in a while...

 

bad mpg is a sign , book says to replace every 60 k , so if you cant rember when its been change then go ahead and do it , The only true way to see how its working is on a scanner , that way you can see if its good , lazy ....change the o2 before the cat or on the cat.

 

Ok so I might just go ahead and replace it but is either better? Or should I ask, are they both just as easy to replace as the other or is one going to give me a headache?

Thanks!

 

The sensors are easy to get to, it's the plugs that can be a bear. Spend the money and replace them. $80 is cheap insurance and your wallet will feel it at the pumps.

 

Ok cool thanks a lot!

 

I have 101k miles on mine and think I'm on the original ones. Don't they usually throw a code when they go bad? The only times I've replaced them is on the Honda when they threw a code.

 

If bad of course they will throw a code , but being lazy will not , but it will hurt the performance and mpg , on a scaner will show spikes thats a good o2 , lasy will lope

 

Eh, O2 sensors are weird. They can go bad, hence the code, OR, they simply degrade, performing their job inefficiently, yet no code is thrown. It's best to change them ~60K miles.

 

I had to replace mine at 112,000 when I installed my new 360. Driving the truck to Illinois from Minnesota with the 318 I got 16MPG. Pulled that engine and installed my 360 and ran into problems with the cat and O2 sensors. No codes though. Replaced both and the new engine ran fine. Go figure.

 

As long as the O2voltage is within range it won't set a code, but like PA said if the sensor has lost it's sensitivity (lazy O2) it doesn't switch fast enough from lean to rich. That can cause driveability problems and loss of economy.