Engine light came on, code reader says cod PO138, Oxygen sensor bank 001, sensor 2. I have searched and read other posts but the all talk about sensors on the drivers side versus passenger. My truck is a 4.7 and there appears to be one catalytic converter and it's on the passenger side going to the single exhaust (maybe the 5.7s have dual exhaust?) also exiting on the passenger. Since it's sensor 2 my guess is it's the one behind the lone catalytic converter (there are two that I see, one before the converter and one after) but want to make sure first. Anyone here familiar with this and can advise? Thanks in advance!

 

yes you are correct. it is the 2nd one

 

Yes, sensor two is the one behind the cat converter. If you had 2 converters like the later models, it would be behind the converter on bank 1 which is the side with cylinder #1 which is the driver side.

 

IDK if it will help but here is that info from AllData. This is the info on P0138. That link is only good for a few days.

https://www.yousendit.com/download/Z...MHdrYUJFQlE9PQ

 

Thanks to all for the replies, very helpful. I replaced the O2 sensor behind the cat and fired it up. Check engine light was still on. Needless to say I was quite frustrated. Ultimately I got it sorted out but thought, in case someone in a similar situation reads this, I would pass along my experience. So, I figured it did not fix my problem but thought I would take a chance that it had to be driven some and brought up to temperature. After a 15 minute drive light still on. Stopped and restarted. Light still on. Then I wondered if maybe it need to be reset. Read about that and saw a few descriptions. One was that it would reset itself after a number of starts but no specific number stated (did not sound likely to me - that should have clued me in .. lol). Another was to disconnect battery for 30 minutes or so and that would reset. And the to take it to someone with a reader and have it reset. My guess was that it would reset itself immediately and hence I had not fixed it. Well, I was wrong, I went to disconnect the battery and decided to start it one last time first and the light was OFF! RIGHT ON! This was after about 5 starts and it seemed to reset itself. And I am glad. Thanks to all the responded, it was a lot of help. Have a great day!

 

PS .. this is a really cool forum.