Check light off: 93 octane gas/pb blast the sensor?

[Stick_man]

My check engine light has been coming on and off now all year. It's now mostly off. It used to be mostly on.

The truck is a '98 v6 sohc w/ 130k miles.

The code is o2 sensor/rich condition p0156.

I bought the sensor and while trying to remove the old one i've coated the thing in pb blaster on more than one occasion (I was still never able to remove it). Do you think that stuff goes past the threads to the actual sensor? Because the darndest thing - the Engine light is off and has stayed off for awhile since.

Also I used 93 octane gas for the first time ever. i have always used 87 octane and rarely fill it up even half way.

Could either of these things have made the light go away or it coming back?

PS - I've also been using fuel injection cleaner in the truck recently too.

 

[ErnieX]

The p0156 code from the O2 sensor is not telling you that the sensor is bad. It is telling you that it is detecting a rich condition in the exhaust that it is sampling. The O2 sensor is probably just fine and doing its job. Something upstream from the sensor is causing the rich condition.

 

[Stick_man]

Well what could be causing to run rich? Also the receipt I have from auto zone does say sensor bad first and running rich as a remote possibility. I guess since the light is off i don't have to worry. Could it just go away by itself? i see the light less and less . . .

 

[coonerboy]

Well what could be causing to run rich? Also the receipt I have from auto zone does say sensor bad first and running rich as a remote possibility. I guess since the light is off i don't have to worry. Could it just go away by itself? i see the light less and less . . .

Leaking fuel injectors or a bad fuel pressure regulator are a couple of things that could make it run rich. Only way to be sure if its running rich is to get a scanner that can check fuel trims. If your fuel trims are ok then I would suspect the O2 sensor. Did you actually replace the O2 sensor?

If any of that PB Blaster actually got to the sensing element(wich I doubt), it would probably do more harm to the sensor than it would do good.

 

[Stick_man]

No the old one is still on there. The new one is still in the box.

I can't get the old one off and since the Check Engine light went out I just stopped trying to get it off.