dam SERVICE ENGLINE LIGHT just came on for the first time :( O2 sensor

[addiction2bass]

well this service engine light just came on this morning for the first time on me. i just started up the truck and backed out of the garage and it pops on and stays. i used my programer to check the code and i just reset it in hopes that it wont come back on BUT it probably will. question is what should these sensors read and do i check them while running or just ignition turned on but dont start motor?

and if it matters its a 1997 C1500 2wd 5.7/auto truck.

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my programmer can read the O2 sensors but hell i dont even know what they are suposed to read or even if i read them running or motor not running.
and hell i dont even know where the bank1 sensor2 is.
i tried to get a video of the sensors running but my camera phone sucks so bad you really cannt see much! ill have to try and get my good camera for a video here in a minute.

always sucks when the check engine light comes on any vehicle and this is the first time its came ON in my truck. 202+K miles on her right now so i know things could use replaced but ill hit them when they come as long as they check good for right now. i just dont want my trucks gas milage or performance to hurt any from this O2 sensor if it does pop back up in dash as bad!


help me figure this thing out and hopefully where the ******* is at so i can replace the right one!

 

[DGA1]

Rear oxygen sensor, the one past the cat, coming from the driver side bank of cylinders. Checking it while the truck is running is perfectly fine. These ones just monitor the performance of the catalytic converters, so no performance, or gas mileage lost. ~$30 from Rock Auto and 10 minutes of your time to replace one and that includes getting yourself a cold one.

 

[addiction2bass]

ok. drivers side pipes rear cat.
and so far my service engine light hasnt came back on yet.
thanks

 

[1997chevydriver]

ok. drivers side pipes rear cat.
and so far my service engine light hasnt came back on yet.
thanks

Remember the cat for the drivers side bank is actually the cat that's on the passenger side.

 

[DGA1]

Remember the cat for the drivers side bank is actually the cat that's on the passenger side.

Exactly! Follow the pipe from the drivers side bank all the way to it's cat.

 

[addiction2bass]

ya i know that.... my truck has true duals so easy to follow the pipes.
and so far it hasnt came back on yet. im hoping it doesnt and it was just a fluke sputter.

 

[Blue95]

Yes you don't have to replace them, but would keep the light off, also if you have not replaced you pre cat o2's, the ones that actually affect MPG and performance you should have replaced them 100K miles ago.

 

[addiction2bass]

LOL well i got the truck with 155ish K miles and this suckers only problems on me for the last 50Kish miles is the fuel pump and brake booster.
im pretty sure the truck was well takin care of before i got it. atleast thats how it seems to me. i didnt get any info on service work to the truck.

and i typically get 15-16mpg which seems pretty good for the way i drive going about 70-80mph to work and back 5days a week or more on my way down to florida i think it was like ruffly 18mpg i believe. been awhile but mileage sounds decent/good to me.

 

[Blue95]

Well that is very good MPG and sounds like all is running well, I am just saying that o2's are due at 100K