So here is the story:

I recently had my brakes changed on Sat 10/27, then went to get some gas. About an hour later, I get the P0171 code on the computer. I go to a gas station later in the week, and the error goes away. It just randomly came back several days ago, right before hurricane sandy in the NJ area. I've been fueling at the same station for the most part, and have had to put a mix of plus and regular with the mess at the stations recently. Is this error usually related to the quality of gas that is put in the car?

 

Should mention, this is a 2007 Acura TL Type S

 

do you try or ever change the gas cap yet?

 

Is this something that I should just reset?

 

P0171 is a lean code for the rear bank. either pcm update or valve adjustment is needed.

 

Meh. Maybe, maybe not (and probably not to valve adjustment).

Let it run and see if it comes back. If it does, probably best to not try and self-diagnose what is causing the code...

The SM says (assuming P0171 is the only code) to check fuel pressure (unlikely since the reading is only on one bank), then valve clearance (I'd say unlikely based on the fact that our valve clearances seem to stay very close to spec), then replace injectors ...

Search around, I think a few have had this code caused by a loose/bad gas cap and also by a faulty A/F sensor in spite of what the SM says...

 

Thats crazy about 5 months ago i was in the acura dealer with this problem i was always adding the correct gas 93 from bp every time. but the code kept coming on they change a map señor and the purge valve sensor and it hasn't come back on since. Since this sandy hit yea its hard to get premium so i had to add regular but addition to the regular i add two bottles of Octane Boost to up the octane number. but i think you having the gas malefaction because of the Regular your adding i think if you add 2 bottles of octane boost u should b good. put regular in mines so i hope it doesnt trip if it does i just run it out when i get up state and refuel with 93 they have it up there

 

I've had this exact same issue in my old 2004 6MT NBP TL. If you're truly running lean, you'll feel a performance difference. I had an auto-part store reset the codes and it came back the next day as running lean on a different bank (light bulb!).

I took it to Acura and they insisted on replacing all 6 injectors, even though I knew this wasn't it, since I had absolutely no power loss. 6 brand new injectors and a week later, it came back. I took it back to Acura and they confirmed what I told them the first time: O2 Sensor. Check your sensors.