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Discussion Starter #1
First of all, thank you to the members on this board for being so helpful!

I have a 2005 2.5 MT PZEV/Cali emissions Outback that is currently throwing a pair of P2098 codes for "Post Catalyst Fuel Trim System too Lean Bank 2". I did a search on here but didn't come up with much.

Following in the footsteps of one thread on here I replaced the air filter, cleaned the MAF sensor with CRC MAF cleaner (though it looked very clean to start with), and looked for obvious vacuum leaks.

I then cleared the code (after which the engine would run like crap at idle after a decel for 3-5 seconds... that lasted about 50 miles), however a day later the code is back. it took 5x starts, 4x short trips (2x 12mi, 2x 5mi) and 1x 3 hour drive to come back on. It returned somewhere on my 45 minute commute this morning. (I've already verified its same code).

I'm hoping to get some advice from you guys on where to go from here, along with a good diagram of the vacuum line system for this car... I haven't had much luck finding one that's particularly helpful to me. Unlike my other car, this one I'm very unfamiliar with in terms of its engine compartment and layout.

Any thoughts on things to test/replace/troubleshoot next?
 

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Often these codes are set due to a failed Front A/F sensor or Rear O2 sensor. You need a scan tool that can read live scan data to determine which is the culprit. Do you have access to that?


Also, verify there are no exhaust leaks first.
 

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Discussion Starter #3
I have a tatrix cable and romraider... and though I used it once upon a time I can't seem to get it working any longer. It tells me it can't find the definition files and I haven't been able to get it pointed at the right file aparently (and the one trouble shooting guide I've found for that tells me to use menu options that don't exist in my version of romraider...). It also doesn't ever connect to the ecu... it just sits there attempting and never connects (there's also no options under the "com" drop down menu).

I know I had all these problems the first time I used romraider... but I can't remember for the life of me how I fixed them or where I got the info on how to.

I'll check for exhaust leaks tonight, as well as continuing to hunt for vacuum line leaks and attempting to get romraider working again...
Any tips on romraider or other things to look at for the code are appreciated meanwhile...
 

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2005 3.0 R n totaled
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Try to switch the fuel - some posters reported that it could be due to bad quality of gasoline. Also, put a can of seafoam fuel additive in the gas tank - see, if that helps after driving it for a few miles.
Also, check the fuel supply and fuel pump for leaks....
 

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Discussion Starter #5
Didn't get much time to tinker with it last night unfortunately. I did attempt clearing the code again, has 3 starts and probably 100 miles on it since the clear.

I did put non-ethanol 91 in when I filled the tank on sunday, as opposed to the regular 87 I normally put in. I'll try grabbing a can of seafoam on the way home for good measure.
 

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2001 VDC/SC One of a Kind
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@juicer. This code refers to the rear O2 sensor staying on lean, low voltage, when the computer knows it shouldn't be.

Likely culprits are the following:
Bad rear sensor(s)
Vacuum leak which would have to be verified by looking at STFT.
Bad grounding - either from the battery to block or any of the several that are in the engine bay
Exhaust leak
Clogged cat

When a heater circuit in an O2 sensor fails, it can't work proper and the voltage signal back to the ECM stays low. An exhaust leak prior to or at the sensor will cause low voltage feedback. A clogged cat will also cause low voltage because flow is restricted.
 

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Had this code thrown right after i bought my 2005 outback. I replaced the lower oxygen sensor using a crowfoot oxygen sensor wrench. These can be found easily at most auto part stores, though I do suggest you call 1st.

Anyway i replaced my sensor and i haven't had a problem since.

I hope this helps

Sent from my SM-G960U using Tapatalk
 

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OK please help with a little clarity... "bad rear"... "lower" sensor(s)?
On the 05 OB I believe there are 3 cat converters and 5 (five) O2 sensors.
2 sensors precat at engine.
2 sensors post cat (bank 1 and 2)
1 sensor on the rear cat
which are you referring to?
More detailed history is that I had the dreaded P0420 for the last 90K miles (currently at 190K miles). Changed passenger cat and pre and post cat sensors on bank 1. Still got the P0420. Threw a resistor on the passenger signal wire for the post cat sensor and P0402 was gone. This P0420 and work was all on bank 1.
Occurring soon after the work, the new P2098 references bank 2.
There is a small exhaust leak at the rear of the passenger exhaust where it joins the driver's side exhaust before the rear cat. Barely audible (slight puffing) but when I pressurized from the rear with shop vac, it is more obvious with water/soap spray.
 

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Lucky me. I think I got all 5. Although I guess the two front are the AF sensors.
So in this event, which sensor(s) do you suspect?
Car runs great and at this point in the lifespan of the car, I am considering a Tactix cable and code suppression...
 

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2001 VDC/SC One of a Kind
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Code suppression doesn't repair the issue. Sometimes it's the sensor and sometimes it's engine performance. It could even be as simple as a bad ground.

Data logging with the tactrix or similar using rom raider can help locate the issue.
 
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