VW 2.0T FSI Engine... System Too Lean Fault Code P0171

DescriptionThis question was asked on the AskDAP Show Episode 5. Q. My VW MK5 GTI has a fault code P0171 the car doesnt seem to idle rough or lose power. What could this be?
VW/Audi parts discussed in this video
Vacuum Pipe for FSI (Genuine VW/Audi)
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Vacuum Pipe for FSI (Vaico)
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Question answered by Paul Barrett, CEO or Deutsche Auto Parts and host of the AskDAP Show.
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[@Deutscheautoparts]

Find all the parts for your VW or Audi! - www.shopdap.com/ - We appreciate your Support and Purchases! - Vacuum Pipe for FSI (Genuine VW/Audi) www.shopdap.com/vacuum-hose-brake-booster-hose-1k0612041gm-1.html Vacuum Pipe for FSI (Vaico) www.shopdap.com/1k0612041gm-20t-fsi-vw-brake-vacuum-pipe.html

[@kaydan9906]

If not a noticeable hissing noise I would vacuum test n80 purge valve and check oil breather,worst case scenario is the rear main seal is leaking that will cause lean fault,check for oil between engine and transmission check O2 sensor reading and spray brake cleaner between the bell housing at bottom there is a small cutout if reading start going crazy it's the rear main....

[@tifffelkner3878]

Love your videos well said!! I have the p171 code its been popping up since june or july decided to take it the taylor vw in findlay,oh they charged 100 dollars for diagnoatics and didnt do any of that just basically did what autzone does..said i needed a new maf i changed it myself the code still kept popping up after that after furthe inspection myself the vaccumm pipe with check valve had a crack in it the dealership wont refund the money..basically moral of the story i thought for 100 dollars i would be getting further testing like smoke testing right on with you stated tell these dealerships that!! They ripped me off!! Now im having to try and find it myself because they stated since i changed the maf the p 171 code is no longer there and there stating a diff code is popping up but i have an obd reader and its still the p171 basically i wanted the issue fixed not them to rip me off :(

[@andrewharwin7139]

Brilliant, thank you, I found the pipes had split exactly as you described. Thanks so much for your video.

[@kashwashwa1]

I had this problem, and my vacuum leak was the brake booster hose.

[@cherokeebriggs510]

What was ur car acting like when you would floor it

[@FabiusMaximus1000]

Mine was the tubes connected to the vacuum pump on the other side from the brake hose. I made a video about it on my channel.

[@senpai_ttc380]

I would like to add something to this that i just experienced. I have the n249 delete sia delet etc. And this code gave me the run around for weeks. Smoke test leak test everything. Well because of those deletes i have bypassed my diverter vacuum line to the throttle body next to bank 1. Well the vacuum side of the diverter when out and was allowing boost pressure to enter after the trottle body right into bank 1. Long story short. New diverter valve fixed it. Sad part about this is a smoke test wont show it

[@REDDMAN1996]

THANK YOU!!!! Because I smoke tested mine and nothing showed any signs of leaking. Rear main seal was already upgraded and valve gasket, cover was done already. MAF sensors and O2 sensors replaced and nothing. So I'm sitting here wondering what it could be. I'll try the diverter valve

[@ads7686]

I had a p0089 at fist then i had a p0171 right after so im thinking its a fuel filter/fuel pressure regulator

[@oceang60smith38]

What is the most common cause of a P0172 on a 2006 A3 FSI BPY? I have replaced many parts including front PCV, VC, N75, DV, supposedly previous owner replaced the HPFP but both sensors still look original. Im about to replace the LPFP because duty cycle at idle is 73%. And Ill do the G410 while Im at it. Haven’t touched the high pressure sensor yet. Also about to replace the rear PCV pipe with check valve. Problem is intermittent but comes with low power, feels like no boost and very high fuel consumption. At times, some smoke emits from the exhaust manifold area not sure if that is possibly some oil being pressed out a gasket and burning or what. Thanks for the help.

[@arronlowley5659]

Can having a decat fitted without the car been tuned cause this fault code to flag? I am off to look at a mk2 cupra R that has this fault code, the current owner states that the car feels no different and doesn’t hesitate etc, he has replaced the pcv, brake booster hose etc and the fault still persists. The car is tuned but was tuned prior to the decat been fitted

[@davidcampbell9670]

i have a 2007 passat 2.0t that is in limp mode wont go over 20 mph i am getting multiple codes p0864 p0687 p0171 p0605 p0601 it is acting like it is misfiring for a second but then clears up but still stuck in limp mode i dont know anything about these cars please help!!!

[@jerryyoung5862]

Had a vacuum leak repair a year ago. Seems like it's back 😒

[@chrisruiz8925]

Paul, I'm having same code on my tsi. smoke test has been done. No more leaks so I'm leaning towards the MAF on its way out giving false readings. any thoughts?

[@trixie9867]

hows your car - i've got a lean code too - 08 tsi@@brlyalve

[@cezarpo]

I have the same SAMEEEEE error i scan my AUDI A3 1.6 75kw 102cv 2008 petrol and hace this error

[@TheFabricolo]

Can a leak in the rear main seal cause the lean system?

[@trixie9867]

yes

[@keithsauer3574]

I'm not having any challenges braking, but I will check the brake booster hose. I do have the same symptoms as the guy who wrote in. I have a whistle turbo noise under heavy boost and maybe it's leaking boost from this check valve on this piece.

[@Gen01Lee]

Keith Sauer I have the same issue and the turbo is under boost and a bunch of other misfire codes, you ever find out what it was?

[@JonnyBeoulve]

Great video thank you.

[@eromanro1961]

P0171 code. No idle issue / no loss of power. Jetta TS1 2009. The other thing is that I know it needs new brakes possibly rotor work. It is possible that the issue of the brakes would be cascading to a P0171 (vacuum booster / airflow issue)?

[@shawnwilson909]

Ever figure this out??

[@sportsmaster00]

I'm having the same issue, needs new rotors and having the running to lean error code..any update?

[@boostedmk5gti563]

Brake booster vacuum hose cracked

[@vesteenoel4877]

I have a volkswagon beetle convertible 1.8 engine check engine light on replaced mass air meter after driving came on again p2187 lean around bank 1 what is that

[@changojuarez1243]

Did you ever find out what was the problem with your car I have the same code on 2012 tiguan

[@changojuarez1243]

Vestee Noel did you find out what was the problem with your car I had the same code on my 2012 Tiguan

[@senpai_ttc380]

Is your 1.8t has the diverter bypassed to intake manifold check you diverter because the vavuum side might be pushing boost pressure into bank one bypass the trottlebody

[@senpai_ttc380]

Easy way to tell is if you take your dv off and blow into the boost side and air comes out of the little vacuum nipple. Then it needs replaced