OBD II Code P0171 "System Too Lean Bank 1"

CLE12GS

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Cleveland
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2012 Buick GS
I cleaned my MAF Sensor with MAF cleaner, and replaced my Evap Purge Valve (just above Throttle Body), and I still get this error message, what should be my next step? I was thinking of getting Seafoam and sucking it into the intake thru a Vacuum Line (but I'm hesitant of doing this since it screws up the Catalytic Converter), and giving it some gas to clean out any deposits on the Intake Valves.

Not sure what else I can try, beside replacing the MAF sensor, I don't suspect the ECM since that hasn't thrown any other codes except this one. Car is running great, except for the cold temps, but it's been flashing this code for about 2 months now, but no CEL
 

'13 Turbo II (216)

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13 regal 05 ranier
Do you live in the area of the deep freeze we just had, did this problem happen during the deep freeze?

I ask because it happened to me also and it was -15 outside. I checked everything that's is recommended and the car was still running perfect. I turned the garage heater on that night and pulled the battery for an hour. Been 4 days and haven't had the code come back up yet.
 

kgoebz

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Ottawa ON
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2012 Buick Regal GS
The cold should not make any difference. That code is almost certainly setting because somehow unmetered air is getting into the motor.

Easiest way to properly diagnose it is to use a smoke machine and fill the intake with smoke (after the MAF) then check for leaks. If smoke is coming out somewhere, the intake isn't properly sealed. Most likely area would be between the MAF and the turbo inlet as that is the vacuum side, where outside air would be sucked into the intake piping. If it was leaking after the turbo it would be more likely to be setting an underboost code (as the pressurized air would be escaping before entering the motor, and the pressure reading on the manifold would have a lower value than the computer is expecting), however it is still a possibility for it to be leaking in somewhere between the turbo and the throttle body, or any of the other vacuum lines on the motor.

The chances of it being a MAF I think are quite small. If it was bad I would expect it to be doing some other weird stuff. Dirty intake valves would also cause different problems (i.e. bad idle, hesitation, etc...), but not a lean code.

I'm also assuming the car is all stock and not tuned or equipped with an intake or highflow filter. All of those things could contribute to this however, if equipped.

Mine has had zero issues and it's been through about a month of fairly regular -30C weather.
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'13 Turbo II (216)

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Your key words are "should not" and I agree, but it doesn't rule it out especially if moisture got onto your filter and has frozen, restricting air flow. Other reasons can be the switching of full types say 87 then e85 and back up to 93 causing issues with the ECU catching up. Yes all those issues you state are the most common problems and can be found out by a simple google search but many people have fixed all those and still have had the code repeat on numerous vehicle brands. It's a very common problem and most of the time it is the PVC valve, if you search opel insignia instead of regal you will find this out.
 

kgoebz

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Ottawa ON
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2012 Buick Regal GS
I'm basing this off of seeing this code come up on numerous vehicles at work over the last decade and I have yet to find one not be related to an air intake leak. This isn't knowledge obtained from googling. Checking the air intake is fairly easy if the OP has basic mechanical skills, but if not it shouldn't take more than an hour of diagnostic time at the dealer or a reputable shop to smoke test it and eliminate the most likely cause. No sense jumping to the worst case of ECU problems or frozen PCVs when there is a far more likely cause that should be less expensive to correct...
 

CLE12GS

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Cleveland
Buick Ownership
2012 Buick GS
Since the DEEP freeze is gone I haven't seen the error pop up, but I pulled the fuses 1,2,5, and 10 for about 2-3 hours about a week ago, No P0171, but now I got a P0455 twice but nothing recent within the last few days. I think I'm going to try some Seafoam in the tank and see what happens.
 

'13 Turbo II (216)

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13 regal 05 ranier
I had zero air leaks,I can do my own smoke tests, no need to have a garage do it when I have my own.
As the op stated, since the deep freeze has been gone and I reset, I haven't had any codes trip at all. Negative 25° can make a lot of things go wacky.
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jpm1172

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8
Buick Ownership
2012 Regal GS
I recently had this code also on ‘12 GS. It has 145000k and also had a cold start rattle which turned out to be a timing chain tensioner that disintegrated as ecotecs weak point is the timing chain set. When the chain loses tension, the ecm and cam phase assemblies will detect that the cams and crank are slightly out of phase so that led to my fault code. My car is impeccably maintained so the intake tract and fuel system is something I focus on regularly during maintenance intervals. Maybe this offers another perspective. Cheers
 

OlSmokie

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Regal
I don't know if you got it fixed, but my '11 Regal was throwing the same code. I put a bottle of fuel system cleaner in it and the light went out. it came back a week later for about 4 hours and then went out and stayed off since then. Been months now without a problem and it is running much better. I'm going to take the advice of another poster on here and run a bottle through every oil change.
 
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