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Oxygen Sensor

brktracer

By brktracer
in Ask A GM Technician

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brktracer Enthusiast

brktracer

Posted
Posted

Hey all I have a DTC code PO161 = 02 sensor heater circut Bank 2 Sensor 2.. Can you tell me which one that is please.. Already checked the fuses and they are good. Didnt have a check engine light. Have a bog problem ..Plugged my Hyperlink scanner in and thats when I found the code. Cleared it and it hasnt come back yet. But would like to know how to tell which sensor it is which for future ref. 99 GMC Sierra Ex -Cab/ 2500 4X4/ 6.0 Automatic Thanks ... Mark

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted

Bank 1 is the side with cylinder #1, bank 2 is the side with cylinder #2.

 

Sensor 2 is the sensor behind the catalytic converter. This one is there to monitor the performance of the catalytic converter and will not cause driveability problems.

brktracer Enthusiast

brktracer

Posted
  • Author
Posted
Bank 1 is the side with cylinder #1, bank 2 is the side with cylinder #2.

 

Sensor 2 is the sensor behind the catalytic converter.  This one is there to monitor the performance of the catalytic converter and will not cause driveability problems.

 

 

 

 

Awesome.. Thanks for the info.. I was hoping maybe that was the one causing the hesitation!! Back to the finding game.. So far I have ruled out everything but the oxygen sensors.. truck was fine before I left.. I guess it didnt like sitting still for 15 months.. Thanks again.. Mark

brktracer Enthusiast

brktracer

Posted
  • Author
Posted
Are you running on the fuel that was in there 15 months ago?  Is so, that's a problem.

 

 

 

 

LOL No already burned through that tank a few weeks ago.. But I thought about that and changed the fuel filter.. Actually it showed up a couple weeks after I got back.. This morning I had the stock exhaust put back on.. Was tired of the noise form the aftermarket one anyway. Plus I Added the Hypertech tune and it seems ALLOT better.. Havent had the hesitation yet.. So keeping my fingers crossed.. Thanks.. Mark

  • 4 weeks later...
brktracer Enthusiast

brktracer

Posted
  • Author
Posted
Are you running on the fuel that was in there 15 months ago?  Is so, that's a problem.

 

 

 

 

 

LOL No already burned through that tank a few weeks ago.. But I thought about that and changed the fuel filter.. Actually it showed up a couple weeks after I got back.. This morning I had the stock exhaust put back on.. Was tired of the noise form the aftermarket one anyway. Plus I Added the Hypertech tune and it seems ALLOT better.. Havent had the hesitation yet.. So keeping my fingers crossed.. Thanks.. Mark

 

 

OK the hesitation is back!! Not as bad but still there.. Of course I have lots of Ideas. Like Oxygen sensors and stuff like that, truck does have over 100,000. I cant seem to figure out if its running lean or rich. However it does not do it when cold. Being cold would be in the rich mode. SO I am guessing it is leaning out.. Could this also be a sign of my fuel pump getting week. And of course it doesnt do it everytime. Wondering about the ECM as well. Every now and then the trans shifts HARD!! If I shut the truck off and restart the hard shift goes away.. Spent 300.00 at the local dealer and problem is still there!! Of course all their Ideas involve $$$ Not saying what they did was bad ( cleaned the injectors, changed wires and checked other areas) But it didnt work.. Anyone have any ideas?? Thanks,, Mark

  • 4 weeks later...
jawzzy Enthusiast

jawzzy

Posted
Posted

 

OK the hesitation is back!! Not as bad but still there.. Of course I have lots of Ideas. Like Oxygen sensors and stuff like that, truck does have over 100,000. I cant seem to figure out if its running lean or rich. However it does not do it when cold. Being cold would be in the rich mode. SO I am guessing it is leaning out.. Could this also be a sign of my fuel pump getting week. And of course it doesn't do it every time. Wondering about the ECM as well. Every now and then the trans shifts HARD!! If I shut the truck off and restart the hard shift goes away.. Spent 300.00 at the local dealer and problem is still there!! Of course all their Ideas involve $$$ Not saying what they did was bad ( cleaned the injectors, changed wires and checked other areas) But it didn't work.. Anyone have any ideas?? Thanks,, Mark

 

 

 

 

 

I had these EXACT same problems(160000Km). Sometimes it runs great (cold), and most times it misses when at idle, and there seems to be a loss of power as well. I just HAD to replace one of my front oxygen sensors, and the truck ran GREAT for a day or so (more power too), but then somewhat back to normal (not as bad as before the replacement, but not as good as the day of either). But I would suggest changing your sensors as well. I couldn't believe the difference.

 

So now I'm looking at changing the other 3 sensors. Problem is GM tells me they're all the same ($105 each), but my mechanic was told by his parts supplier that the front 2 were different than the back 2, and twice as much too ($180 for fronts, and $95 for backs). Above GM-Tech states "Sensor 2 is the sensor behind the catalytic converter. This one is there to monitor the performance of the catalytic converter and will not cause driveability problems". So does that mean I shouldn't bother with the back 2 sensors?

Mr. Smith Enthusiast

Mr. Smith

Posted
Posted

 

OK the hesitation is back!! Not as bad but still there.. Of course I have lots of Ideas. Like Oxygen sensors and stuff like that, truck does have over 100,000. I cant seem to figure out if its running lean or rich. However it does not do it when cold. Being cold would be in the rich mode. SO I am guessing it is leaning out.. Could this also be a sign of my fuel pump getting week. And of course it doesn't do it every time. Wondering about the ECM as well. Every now and then the trans shifts HARD!! If I shut the truck off and restart the hard shift goes away.. Spent 300.00 at the local dealer and problem is still there!! Of course all their Ideas involve $$$ Not saying what they did was bad ( cleaned the injectors, changed wires and checked other areas) But it didn't work.. Anyone have any ideas?? Thanks,, Mark

 

 

 

 

 

I had these EXACT same problems(160000Km). Sometimes it runs great (cold), and most times it misses when at idle, and there seems to be a loss of power as well. I just HAD to replace one of my front oxygen sensors, and the truck ran GREAT for a day or so (more power too), but then somewhat back to normal (not as bad as before the replacement, but not as good as the day of either). But I would suggest changing your sensors as well. I couldn't believe the difference.

 

So now I'm looking at changing the other 3 sensors. Problem is GM tells me they're all the same ($105 each), but my mechanic was told by his parts supplier that the front 2 were different than the back 2, and twice as much too ($180 for fronts, and $95 for backs). Above GM-Tech states "Sensor 2 is the sensor behind the catalytic converter. This one is there to monitor the performance of the catalytic converter and will not cause driveability problems". So does that mean I shouldn't bother with the back 2 sensors?

 

 

 

 

 

The fronts and rears are different. The fronts are the important ones, that backs as posted just monitor the cats. They will set a code though. So if you have a MIL and it is from the rears then you can change them or ignore the light. You can get the rear o2 sensors cheaper at Advance or Autozone.

jawzzy Enthusiast

jawzzy

Posted
Posted

Actually, after some more research yesterday, its turns out on the 2001 4.8L ONLY, all 4 sensors are all the same part #. Seems they tried something different on that year model for some reason. When I ordered these through the GM dealer, they used my serial #, not my engine specs to find the part numbers. But when you call a parts dealer and use the specs, they say the fronts are different than the backs, and TWICE as much too:(

00Tahoe Enthusiast

00Tahoe

Posted
Posted

I am confused or maybe not. The O2 sensor in the rear is to monitor the cat. conv. and does not affect driveability correct? Now, if an option is to ignore it, then why is it there?

 

My feelings are that it is there to monitor the cat. conv. and if it is setting a code, then there might be an issue with the cat, which in itself can affect driveability. So therefore, I would not ignore what the sensor is telling you. It may be okay, but the cat may not.

 

There might be a possibility of a clogged cat on your vehicle.

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