Help with po138 code

Thanks it was the front air/fuel sensor putting the blame on its downstream sniffer

 

Glad to hear you got a solve on this.

I know you probably thought I was crazy when I said this on my first reply:

What you've experienced is not remotely uncommon. It really is best to replace both upstrame/downstream sensors any time one sensor on a bank when one goes bad, and you just learned why

 

I am having the the same or at least similar issue. P0138 confirmed and P2195 pending. I have replaced sensor 2 bank one (NTK not Denso Not sure if that is good or bad based on what I read in this post so far so thanks all for the oh crap feeling LOL). Clear the codes and nothing happens while running around town. Engine starts and runs like a dream lots of power and smooth as silk. But get out on the highway and within 1/2 an hour it sets the code but still goes like a scared rabbit. Based on the fact that it only trips at highway speeds I kind of ruled out a wiring issue. inlet and outlet temps between left and right cats seem to stay well matched. I may try swapping upstream sensors from left to right but was wondering about other possibilities or things to look for preferably on the simpler side of things first. Like maybe pulling and reading my plugs for discrepancy between cylinders. I added a copy of the freeze frame if anyone knows how to decipher it, I don't.

 

Yep, Denso....live and learn

Unfortunately, even on a 2nd Gen like yours, the front sensors on our 1st Gens are just as difficult to get to.

P2195 pending = Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1)

The end note from your freeze frame in bold below is not far off.
If possible, always consider at least changing both up/down stream of which ever bank is setting code when dealing with oxygen sensors.


Downloaded pdf and exported to spreadsheet for easier viewing..