Replaced My O2's. They Have Seen Better Days. (1 Viewer)

[harrydunn]

Started throwing a code 21 three weeks ago so decided to swap them both out. CEL is gone. I never calculate mpg but figured I would before I changed them. My last tank of gas was around 9.75 mpg and was all in-town between 25-50 mph. A lot of heavy snow driving and extended idling so this number is slightly skewed. I'll be curious to see if my mileage increases. I'll post up in a week or so when I burn through a tank with the new OEM sensors.

Old sensors say "NTK Japan" on them. The one on the right was throwing the code. The left one doesn't look as bad, relatively speaking. Were a bit of a pain to get off but not as bad as some have experienced. One nut was completely rounded off so it took an hour or so to get off with PB, heat, and vice grips. The other three took a combination of 10, 11 and 13mm sockets. 12mm no longer fit any of them.

The ugliness:

 

[94SRUNNER]

WOW....you arent kidding! New ones are in, thats good, as I am sure your 80 thanks you.

Where did you pick the new ones up at?

 

[harrydunn]

Picked them up from gotmud.

 

[94SRUNNER]

Excellent!

 

[Kernal]

Anyone know if O2 sensors can be cleaned to improve performance?? IDK.

 

[harrydunn]

I've heard of others doing this before but I don't recall what results they obtained.

 

[Jrob80]

I just put new 02's on a couple weeks ago I was throwing a PO171 I started in there and the nuts were rust real bad, had to take it to a shope to get them off. I am pretty sure they were original ones. Took care of the code.

 

[StopGap]

That's a good question...

I was just having that same discussion with a processes engineering buddy. Evidently an O2 sensor has 4 parts, a heater, platinum coated electrodes, zirconium dioxide (ZrO2) as an electrolyte medium and a porous ceramic "thimble" to hold the ZrO2 and the electrodes in the gas stream.

As the ceramic gets clogged exhaust gas has a hard time making it to the ZrO2, the sensor starts becoming slow. If they get contaminated with oil, the oil carbonizes in the ceramic. Those things get hot 360C min. A problem is most ecu are designed when the O2 sensor goes wrong, it enriches the fuel mixture, further clogging the sensor.

We came to the conclusion there would be no easy way to clean out the porous ceramic. Once the carbon is in there there is no easy way to make it soluble to remove.

One way may work, if the contaminated sensor was placed in high temp and a pure/high O2, then the carbon may convert to CO2. Then again it is worth all the trouble ?

 

[harrydunn]

That's a good question...

A problem is most ecu are designed when the O2 sensor goes wrong, it enriches the fuel mixture, further clogging the sensor.

I'll vouch for that. Things have definitely been smelling rich for several months, even before the light kicked on.

 

[greentruck]

Anyone know if O2 sensors can be cleaned to improve performance?? IDK.

Even if you could, the corroded threads would get you in trouble trying to put them back in, if you didn't destroy them getting them out in the first place.

And they rarely cause a problem before they are transformed into the corroded mess above.

 

[madcardisease]

Mine is throwing a P0420. Could that have something to do with sensors also, or is it strictly a CAT code?