Code explaination. OBD2 (Jimmy)

So I got my hands on a OBD2 reader - and with my engine light on I decided to get it read and it shows the following:

Code: 140 (No activity noted O2 sensor - Bank1 sensor 2)
Code: 118 (engine coolant temperature circuit high input)

Now, Ive erased the code and it hasnt popped up yet... Been driving for a day or so. Could this mean that it throws an error code 'once in a while' to produce an engine code? Is this even an issue???
or Should I be replacing the sensors? cause I assume that the temperature sensor for the dash is reading ok (within normal operating range)?

Now my next question is what o2 sensor is located at Bank 1 sensor 2? Diagrams?? - drivers side or passenger side? before or after cat?

Sorry for my ignorance in these matters... electrical diagnosing is not my forte. Thankyou for your help.

So I got my hands on a OBD2 reader - and with my engine light on I decided to get it read and it shows the following:

Code: 140 (No activity noted O2 sensor - Bank1 sensor 2)
Code: 118 (engine coolant temperature circuit high input)

Now, Ive erased the code and it hasnt popped up yet... Been driving for a day or so. Could this mean that it throws an error code 'once in a while' to produce an engine code? Is this even an issue???
or Should I be replacing the sensors? cause I assume that the temperature sensor for the dash is reading ok (within normal operating range)?

Now my next question is what o2 sensor is located at Bank 1 sensor 2? Diagrams?? - drivers side or passenger side? before or after cat?

Sorry for my ignorance in these matters... electrical diagnosing is not my forte. Thankyou for your help.

Turn your key to the "run position" (a click or two forward where the radio comes on and the warning lights turn on but the engine doesn't run). Make sure the check engine light still turns on. Some OBDII testers (cheaper ones) can fry\lock up the system and make the check engine light not come on anymore. I've never seen it happen, but heard of it. Turning the key forward will tell you if it's working fine.

If the light does come on you know the check engine circuit is functioning fine and those codes may have just surfaced by accident (loose wire) or for no apparent reason. I had an O2 check engine code pop-up on my jimmy, I noted the engine was running perfectly fine (although a VERY crooked dealership had done some work on it previously) so I erased the code knowing the worst that could happen was it would just come back on (if the part was ACTUALLY broken). Months later and almost 10,000 on the odo and the code has not returned, not even a pending code. Must have been a fluke (or a fix up from that stealership). hth

I cleared the code with my code reader but my question is if I simply removed the battery terminals, would this clear the codes??

Also, assuming that a faulty sensor is the reason for the code - by starting the truck again after removing the codes; Would these codes show up right away??? or will it take a couple days for the computer to reset?

I cleared the code with my code reader but my question is if I simply removed the battery terminals, would this clear the codes??

Also, assuming that a faulty sensor is the reason for the code - by starting the truck again after removing the codes; Would these codes show up right away??? or will it take a couple days for the computer to reset?

The codes should show up right away or within the first 10 mins of driving, the computer will run a full diagnostic as you begin driving and it will poll each sensor looking for faults. If it doesn't show up within a day I would imagine the codes just popped in by a fluke, it's not like GM worries about the computer jumping the gun on a possible issue, each time that light flicks on all they see if dollar signs.

The codes should show up right away or within the first 10 mins of driving, the computer will run a full diagnostic as you begin driving and it will poll each sensor looking for faults. If it doesn't show up within a day I would imagine the codes just popped in by a fluke, it's not like GM worries about the computer jumping the gun on a possible issue, each time that light flicks on all they see if dollar signs.

Well, I erased the codes, although after a day of driving, code 118 showed up (coolant temp sensor hi input) - so decided to change the coolant. Code 140 has not showed up just yet.