[Lowcountry idn]

I did what you said to do twice. Here are my results. View attachment 131533 View attachment 131534

I did what this guy said to do with the propane torch and didn't find any leaks although I am not sure exactly which lines I am supposed to check.

Your long term fuel trim on bank 1 is staying pretty high both times. 5.5 isn't terrible, but ideally it should run consistently less than 5 like it is on the other bank. Holding idle steady - with a small vacuum leak I would think the LTFT would come back closer to normal than 5.5 Like I said, you can't for sure rule out a vacuum leak, but I think this points towards something else.

If it were mine I would spend the money and change the primary air / fuel sensor with a Denso - there like 80 bucks on rockauto or amazon.

Trying to find a vacuum leak is really, really hard. With the propane torch our ECU reacts so quickly you won't notice it directly, and also any vacuum leak that will affect only one bank is going to be at the bottom of your intake plenum - which you can only access one side of while running anyway - and even that side it tough to reach. Your only real chance is have someone watch the STFT closely and you should see it spike as you pass by with the torch, if you do have a vacuum leak.

 

[cody0707]

Your long term fuel trim on bank 1 is staying pretty high both times. 5.5 isn't terrible, but ideally it should run consistently less than 5 like it is on the other bank. Holding idle steady - with a small vacuum leak I would think the LTFT would come back closer to normal than 5.5 Like I said, you can't for sure rule out a vacuum leak, but I think this points towards something else.

If it were mine I would spend the money and change the primary air / fuel sensor with a Denso - there like 80 bucks on rockauto or amazon.

Trying to find a vacuum leak is really, really hard. With the propane torch our ECU reacts so quickly you won't notice it directly, and also any vacuum leak that will affect only one bank is going to be at the bottom of your intake plenum - which you can only access one side of while running anyway - and even that side it tough to reach. Your only real chance is have someone watch the STFT closely and you should see it spike as you pass by with the torch, if you do have a vacuum leak.

I ordered a new sensor. I’ll swap it out and see if it changes anything. If not I’ll begin the hunt for a small hole. Thanks for the help.

 

[Roko11]

I ordered a new sensor. I’ll swap it out and see if it changes anything. If not I’ll begin the hunt for a small hole. Thanks for the help.

Hey, so did the new sensor end up resolving the issue for you? I am having same code after cat/o2 replacement and am leaning towards sensor but confirmation would be nice.

 

[cody0707]

Hey, so did the new sensor end up resolving the issue for you? I am having same code after cat/o2 replacement and am leaning towards sensor but confirmation would be nice.

Yes the new sensor solved my problem.


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[FishCannon]

Sorry to revive an old thread...

My son just bought his first car, a 2011 Pro4X. It's got a P0171 code for Bank 1 Lean Condition.

I've cleaned the MAF as a precaution, and looking at the live data at idle, the STFT is either 0% or 25%. Nothing in between. It'll sit at 0 for a few seconds, then 25 for a few seconds. The truck runs great. I'm assuming that the problem is the A/F sensor due to the STFT readings. The drivers side sensor appears to be original, with a grey cover over the wires, while the passenger's side appears to have been replaced, with a blue cover.

So, I have 2 questions:

1> The heater core outlet fitting is seeping coolant that drips directly onto the A/F Sensor. A new fitting is already ordered. Could the coolant leak cause the sensor to go bad?

2> I'm seeing conflicting info regarding bank 1 vs bank 2. Which side is which? Is Bank one on the driver's side or passengers' side?