Directly, it does not control the A/F ratio. However, the PCM uses information that it provides to control the A/F ratio (along with bits from other sensors as well).

That means you ran in open loop the entire way. You probably ran rich, as the PCM runs by a "template" program in open loop mode, meaning you used more fuel than you could have if you had had the sensors plugged in.

These trucks get mediocre gas mileage as it is. Dropping from barely double digits to single digits, along with a constant CEL, is not a good solution. You will spend more on fuel after a short period of time than a new sensor would cost you.

 

You need a new mechanic.

 

haha wow. i dont think ive ever met such a hard headed person in my life.

your mechanic is a dipschit. i did read my quote, and i know what it says. you go ahead and run with your o2s unpluged, and enjoy your schitty gas mileage, and continuous CEL. You can keep running in open loop with decreased fuel economy.

please explain to me how a wrong value is a miss-fire?

also explain to me how i dont know what im talking about when youre the one who gets advice from a mechanic that tells you to just unplug the o2 sensors.

now, back to the OP, yes replace that sensor ASAP. Dont just unplug it.

 

I'll be more than happy to explain it to you - a wrong value will make the mixture too rich or too lean which will lead to misfire. Its that simple.

Im not saying dont replace the O2, im saying to run the truck with it unplugged, rather than with a misfire, until you get the $ to replace it. With my v-10 i want to get as good mpg as possible, thus i did change my O2 sensors as soon as my trip was over.
Bottom line - run your truck without the O2 until you replace it, do not keep that faulty O2 plugged or the misfire will mess you up.

And a word of caution - there is a good chance that you will strip the thread when removing the O2 sensor. If this happens, you are better off welding that thread shut snd drilling/welding a new one, or your new sensor may take a dump very soon after.

P.s. the tahoe was getting 24mpg highway, so GM may have better default a/f value

 

wow. there's some unnecessarily strong fighting words here.
atlrus is right. the O2 is just a sensor that feeds info to the pcm, and a bad reading can cause the pcm to make incorrect decisions that lead to misfire, popping, etc. if that's the case, its better to unplug the O2. lack of O2 signal will lead the pcm to use default values which will be a tad rich, and while it won't get ideal mpg, it will at least run, even for 100,000 miles if you choose.

back to original poster Ed. replace your front O2 and report back. good luck.

 

Um. Pretty confrontational for a newbie....... Not really a good idea.

And yes, the O2 sensor DOES have an effect on fuel mixture. The PCM uses the data gleaned therefrom to ALTER injector pulse width. Unplugging them and constantly running in open loop is wasting gas. The manufacturers used those sensors for a reason, and you assuming you know better than they, what the reason is, is just arrogance. You are crippling your computer by removing that data. Will it 'harm' the engine? No, not really. At least, not immediately.... but, is it a "good idea". No. It most certainly is not.

 

Well, im not going to be dragged into a snobbish conversation on who has how many posts. But answer this - are you saying its better to run a faulty O2 sensor with constant misfire rather than unplug it?

The OP already said he cannot get a new sensor right away. So he is left with those 2 options.004x41500 claims that its better to run misfiring engine than to unplug the O2. I call this BS and i dont care how many posts i have.

P.S. Running without O2 sensor will not hurt your engine, not now, not ever, period. O2 is all about mpg, that's why the "manufacturers" have it on. And I can say this because I had the same problem recently and did a ton of research on the O2 sensors, plus I have a 1st hand experience.

 

No. It isn't better to run a faulty one, however, by some of your claims, you seem to think it is better to not run one at all..... Is this not the case?

And I am not being 'snobbish'...... My reasoning there is, you are relatively new here, do you want to establish yourself the reputation of being confrontational? That isn't really conducive to lasting very long...... How you conduct yourself is at least as important as what you have to say. Just friendly advice.

 

I see what you are saying, im not confrontational, just passionate

And i said that its better to run without O2 sensor than with a faulty one, as well as that not having the sensor will not hurt your engine at all.004x41500 told the OP to plug back the sensor, which is a really really bad advice! And because he has more posts than i, the OP would likely had followed his advice and ran a misfiring engine... stuff like that really grind my gears and i appologise for anyone offended...except to 004x41500, who should appologise to the OP for messing with his engine in such way...

 

I thought, like most here I think, that you were instructing to run without the sensor, period, that it was not needed. Since that is not the case, I apologize if I came off pretty strongly in my reply.

To the original poster, like others have said, replace the O2 sensor when you can. Until then, run without it plugged in.