How important is the O2 sensor?

[jkilling]

Several weeks ago I reported that I had engine codes 15 and 17 on my 1990 Festiva. 15 being the O2 sensor I ordered a new one. After a search of this site I have tried to remove the sensor with the suggested repeated baths of PB Blaster, warm engine, cool engine with torch,cheater bar, all with no success. I do not have an impact wrench, so that's one idea I haven't tried. So, before I proceed any further, how important to the efficient operation of this engine is the O2 sensor. I have unplugged mine and there was no apparent change in fuel mileage (46 mpg) or engine performance so I am assuming it does not work and wondering just how important it really is. Is it worth the risk of possible damage by hiring a mechanic with an impact wrench and the possibility of having to re-thread the opening? Should I just clip the wire and leave the dead 02 sensor lie?

As for the engine code 17, I tried the recommended Sea Foam when I filled the tank. Engine almost immediately started cutting out going up the moutains here in western NC. Decided to not get too excited and wait until next tank of gas. Refilled without additive and have had no problems since. Bad gas? Or did the Sea Foam carry something thru the injectors? Anyway, car is running good. Wife says I'm annal, just let it be and sometimes, she is right.

[FestYboy]

had you come to festiva madness in Raliegh, i could have taken care of that for you...

the o2 is manditory for proper fuel enrichment adjustment. if the ECU doesn't see it, the ECU will throw a code and substitute a "safe" value (read: rich).

[WmWatt]

Another way of loosening a frozen nut is to put a wrench on it and tap on the other end of the wrench with a hammer. Does much the same as an impact wrench but gives you more control.

I bought a set of impact sockets on sale and use them with a T-bar socket driver and a hammer in the same way. If you have the special O2 sensor socket that method would also work.

[scitzz]

Is it possible that the O2 sensor was cross threaded before you tried to take it off, say, by a previous owner?

[jkilling]

Thanks for all the info. Sounds like I should continue to try to get the O2 sensor out. Would love to come to the Rally, but I am a Park Ranger and have to work weekends. Saw the pictures, afraid mine isn't as pretty as most, although here in Wilkes and Ashe counties, mine doesn't look so bad. I'll keep trying.

[Pu241]

Would love to come to the Rally, but I am a Park Ranger and have to work weekends. Saw the pictures, afraid mine isn't as pretty as most, although here in Wilkes and Ashe counties, mine doesn't look so bad. I'll keep trying.

Doesn't matter what it looks like!
It runs and is at the meet, those are the most important points.
Understand about working, but at least for FM and most Ohiostiva's there is a pre-meet which is almost as much fun as the meet itself.

Plus you are 2 hrs/88 miles from the biggest Festiva fan family I know of.
Drop a line to Ladyblaster and/or Motoxpress for their next mini-meet.
You wont be disappointed!