Threw a code shortly after changing both upstream O2 sensors. I replaced the sensor in question and the code still persists. I've been doing some research on this code and I haven't had any luck finding information on the codes occurring after the sensors were changed.

Is it possible to have a vacuum leak someplace?

Truck is a '99 5.4 with 146k.

Any help is greatly appreciated.

 

This code is for the passenger side upstream O2 sensor. Did you have the code before you changed the sensor out? I assume yes since you said it "still persists." I had the same code, but replacement fixed mine.

But, in my research, I recall posts about the connection on this particular O2 getting gummed up and corroded from coolant lines (maybe A/C lines too?) dripping on to it. I recall someone on here even replaced the wiring harness that goes down to it because it was so corroded. On the old sensor, check the plug to see if that is corroded in there. Might be a possibility.

Another possibility might be that you got a bad sensor? Probably unlikely, but could happen. Swap your passenger/driver sensors and see if the code swaps sides. If it doesn't, you know it is probably above the sensor somewhere. Good luck.

 

I believe the code is for the drivers side O2 sensor. The code came on after changing both upstream O2 sensors. Went to have the code read and replaced the drivers side and the code came back.

 

Any takers?

 

Sound like to me you got a good answer - Good post jmg-in-alaska

Check your work .

 

Just got the truck back from the mechanic and he fixed the problem for me. As for jmg-in-alaska's post, it was completly accurate. The code is infact for the passenger side and that upstream O2 sensor was causing the problem. When I installed the O2 sensor I bent one of the prongs which caused a bad connection and threw the code.

I'm updating this post so others can use it as a reference if need be. Once again jmg-in-alaska, thanks for the good post.

 

Glad to hear you got it fixed. Hope it didn't cost you too much. We're all learning with these things on a daily basis for sure. You won't make that mistake again.