# Getting random lean code p0171



## Vinnyty (Mar 19, 2008)

:screwy:Hey everyone I keep getting a random lean code p0171 (generic scanner) I DO HAVE A ROSSTECH VCDS. Im wondering what I need to pull from the vagcom as far as fuel trims and logs in order for someone to make sense of it and to help me figure it out. I also dont know how to do this. :screwy:

Car is a 2007 VW passat 2.0t automatic


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## Uwe (Jan 16, 2000)

Start here:
http://www.ross-tech.com/vag-com/cars/fuel-trim.html

-Uwe-


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## Vinnyty (Mar 19, 2008)

-1.4% on idle and 19.1% on partial. that doesnt sound good being 19.1%


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## Vinnyty (Mar 19, 2008)

anyone?


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## Uwe (Jan 16, 2000)

Did you do the sanity test on the MAF as suggested in the last paragraph of the Fuel Trim article?

-Uwe-


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## Vinnyty (Mar 19, 2008)

Thanks Uwe. Now that I can get some traction ill do the maf test. I should get the dealership to buy your software maybe they will be able to figure it out next time. 

I will post results.


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## Vinnyty (Mar 19, 2008)

ok so i just did a run in second almost pegging it, pegging it enough so that it doesnt shift to 3rd in tiptronic. 

Lambda idle self adapt value: 1.2 %
Lambda partial value adapt: 6.6%

Seems like it is a maf on its way out like you guys said. :screwy: the car runs lean and runs like crap off and on and I can usually tell when its running lean and the light is about to come on. 

Got the new factory airbox coming and dealership says its the cold air intake from forge and wants the oe box back on for further testing.


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## Vinnyty (Mar 19, 2008)

also doing a run in 2nd nearly redlining for about 5 seconds was showing 60-80 g/s on group 003 block 2.


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## Vinnyty (Mar 19, 2008)

Hopefully I can get this thing fixed soon and I hope its something simple like the maf.


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## Vinnyty (Mar 19, 2008)

bump


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## Uwe (Jan 16, 2000)

If you're only getting 60-80g/s at full throttle in second gear, at 5000-6000 rpm, then it's real likely that your MAF is shot.

-Uwe-


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## Vinnyty (Mar 19, 2008)

Im getting my factory air box tomorrow. So i will reinstall, retest and bring to dealership and let you guys know the results.


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## Vinnyty (Mar 19, 2008)

So put everything back to stck. All levels are perfect so far. Idle is at 0% bcause of reset and haven't had the car idling yet. Lambda partial is at 0.8 so far and mass air flow read 160-180 at 2nd redline

So what do I tell forge about the intake? And should I send it back?


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## Vinnyty (Mar 19, 2008)

idle is at 0.8 and mult is at 1.6 did about 30 miles today with the factory setup. MAF still reads 160-180. Would below 20 degree weather cause issues like this with the intake? Also I noticed the intake manifold temp sensor seems to be missing some coating on the sensor contacts not sure if this has anything to do with it.


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## Vinnyty (Mar 19, 2008)

I am so stumped :*(


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## Vinnyty (Mar 19, 2008)

anyone?


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## Uwe (Jan 16, 2000)

Well, your fuel trims and MAF readings now seem OK, so the question is: What changed? 

If I understand this correctly, you had an aftermarket intake on there, and were showing a max of 80 g/s on there, along with bad fuel trims which that would be expected to cause. Now you've a stock intake on there, and all is well, right?

Since I can't fathom how an aftermarket intake would cause the MAF to read low by half, I'm gonna ask: Did you disconnect and reconnect the MAF or any other wiring in the process of swapping the intakes?

-Uwe-


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## Vinnyty (Mar 19, 2008)

Yeah I disconnected the maf connection to install the factory box back up.


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## Vinnyty (Mar 19, 2008)

but the only thing is, i also disconnected the maf with the air intake and ran the car with it unplugged to see if i got a performance difference. So its been unplugged and plugged back in since.


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## Uwe (Jan 16, 2000)

OK, one possibility that you have a dodgy connector at the MAF, potentially due to corrosion. Unplugging it and re-plugging it will often fix such a problem temporarily. I would drive the car until the symptoms return, then unplug and replug the MAF. If that fixes it, then you can be pretty sure you've found the problem.

-Uwe-


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## Vinnyty (Mar 19, 2008)

You know what is funny. originally forge had sent me the wrong intake elbow going to the turbo. IT was HUGE! so i got the correct one in and cleaned everything and reinstalled the intake and drove it for about 50 miles (this was before i got the vcds) and the light went out on its own so you could be on to something maybe when it went away because i unplugged it then plugged it back in.


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## vwemporium (May 27, 2002)

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## Vinnyty (Mar 19, 2008)

So Slowhatch and mochavdub are having the same exact issues as me. When i say same exact i mean same exact. Ive asked them to provide me with MAF part numbers and try to put it back to stock.

We have determined the cause is the forge intake and the cold weather. they are both in below 30 temps and car runs like its in limp mode after.


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## Vinnyty (Mar 19, 2008)

So mike from forge motorsports is claiming that due to the extra air that the fuel pump cant keep up. is there a way to monitor the fuel pressure to prove this theory?


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## Uwe (Jan 16, 2000)

Try Measuring Blocks, group 230.

-Uwe-


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## Vinnyty (Mar 19, 2008)

so if this is the case and it is not getting enough fuel supplied. Would a fuel pump upgrade and ecu chip resolve this?


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## Dana @ Ross-Tech (Sep 15, 2009)

Normally the mechanical failure of the HP fuel pump (and/or) lifter -or- the failure of the low Psi switch set specific fuel related faults. Do you have a recent scan handy?

I don't want to lead you off course ... but the loss of vacuum or lean condition may be caused by a faulty or incorrect crankcase breather valve:

http://wiki.ross-tech.com/wiki/index.php/Special:Search?search=oil+cap

Pull the oil cap at idle and see if its sucked on, nearly requiring two hands to remove. If no vacuum is found I'd say drop that theory, but if it won't come off easily I'd look into that recall and make sure the proper valve is installed.


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## Vinnyty (Mar 19, 2008)

So it looks like im doing pretty good stock. specified is 110 under heavy load and the actual is 110-112 and difference gets no higher than 2.5%. my idle lambda is 0.1 and the mult is 0.4%


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## Vinnyty (Mar 19, 2008)

you know whats funny is when i remove the oil cap it does suction. but i showed this to a tech at vw before and after he replaced the pcv to the newest revision he stated "thats normal"


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## Vinnyty (Mar 19, 2008)

Here is the most current scan:

Tuesday,08,February,2011,13:39:27:04884
VCDS Version: Release 10.6.3 (x64)
Data version: 20101206



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--------------------------------------------------------------------------------


Chassis Type: 3C0
Scan: 01 02 03 08 09 15 16 17 19 1C 25 42 44 46 52 53 56 62 65 72


VIN: WVWJK93C37P081635 Mileage: 73320km/45558miles

00-Steering Angle Sensor -- Status: OK 0000
01-Engine -- Status: Malfunction 0010
02-Auto Trans -- Status: OK 0000
03-ABS Brakes -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: Malfunction 0010
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: Malfunction 0010
1C-Position Sensing -- Status: OK 0000
25-Immobilizer -- Status: OK 0000
42-Door Elect, Driver -- Status: OK 0000
44-Steering Assist -- Status: OK 0000
46-Central Conv. -- Status: OK 0000
52-Door Elect, Pass. -- Status: OK 0000
53-Parking Brake -- Status: OK 0000
56-Radio -- Status: Not registered 0011
62-Door, Rear Left -- Status: Sporadic communication error 1000
65-Tire Pressure -- Status: Not registered 0001
72-Door, Rear Right -- Status: OK 0000

-------------------------------------------------------------------------------
Address 01: Engine Labels: 06F-907-115-AXX.lbl
Part No SW: 3C0 907 115 S HW: 8P0 907 115 B
Component: 2.0l R4/4V TFSI 0020 
Revision: 5BH15--- Serial number: VWZCZ000000000
Coding: 0404010A19070160
Shop #: WSC 08081 444 04514
VCID: 306517EEDAA5

1 Fault Found:
008567 - Bank 1; System Too Lean off Idle 
P2177 - 001 - Upper Limit Exceeded - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10100001
Fault Priority: 2
Fault Frequency: 10
Mileage: 73086 km
Time Indication: 0
Date: 2011.02.06
Time: 11:52:37

Freeze Frame:
RPM: 1682 /min
Load: 19.2 %
Speed: 84.0 km/h
Temperature: 88.0°C
Temperature: 7.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 14.478 V

Readiness: 0000 0000

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Address 02: Auto Trans Labels: 09G-927-750.lbl
Part No SW: 09G 927 750 HJ HW: 09G 927 750 FP
Component: AQ 250 6F 1068 
Revision: 00H38000 Serial number: 
Coding: 0000072
Shop #: WSC 08081 444 04514
VCID: 8005072EAA85

No fault code found.

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Address 03: ABS Brakes Labels: 3C0-614-095-C2.lbl
Part No SW: 3C0 614 095 S HW: 3C0 614 095 S
Component: ESP 440 C2 H015 0004 
Revision: H015 Serial number: 0668062402
Coding: 0013755
Shop #: WSC 00028 028 00001
VCID: 32611DE6D4A9

No fault code found.

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Address 08: Auto HVAC Labels: 1K0-820-047.lbl
Part No: 1K0 820 047 FP
Component: Climatic PQ35 120 0606 
Shop #: WSC 00000 000 00000
VCID: 77F7ECF27F4B

No fault code found.

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Address 09: Cent. Elect. Labels: 3C0-937-049-23-H.lbl
Part No SW: 3C0 937 049 Q HW: 3C0 937 049 Q
Component: Bordnetz-SG H46 1501 
Revision: 00H46000 Serial number: 00000006190688
Coding: 08840F1340041A005B0000000F00000000285D435C0000
Shop #: WSC 00028 028 00001
VCID: 37772CF23FCB

Part No: 3C1 955 419 
Component: Wischer VW461 001 0101 
Coding: 00063445
Shop #: WSC 00028 

1 Fault Found:
01333 - Door Control Module; Rear Left (J388) 
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 2
Fault Frequency: 1
Reset counter: 112
Mileage: 73240 km
Time Indication: 0
Date: 2011.02.07
Time: 13:17:00

Freeze Frame:
OFF 
Voltage: 12.35 V
OFF 
ON 
OFF 
OFF 
OFF 


-------------------------------------------------------------------------------
Address 15: Airbags Labels: 3C0-909-605.lbl
Part No SW: 3C0 909 605 N HW: 3C0 909 605 N
Component: 09 AIRBAG VW8R 031 2522 
Revision: 12031000 Serial number: 003B2PM7KP3W 
Coding: 0012345
Shop #: WSC 00028 028 00001
VCID: 316312EAD1AF

Part No: 3C0 959 339 B
Component: BF-Gewichtsens. 007 0003

No fault code found.

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Address 16: Steering wheel Labels: 3C0-953-549-SW20.lbl
Part No SW: 3C0 953 549 H HW: 3C0 953 549 H
Component: J0527 0015 
Revision: 00006000 Serial number: 3C5953507R 
Coding: 0002013
Shop #: WSC 00028 028 00001
VCID: 316312EAD1AF

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments Labels: 3C0-920-xxx-17.lbl
Part No SW: 3C0 920 971 A HW: 3C0 920 971 A
Component: KOMBIINSTRUMENT VD1 1614 
Revision: X0006000 Serial number: 00000000000000
Coding: 0007205
Shop #: WSC 00028 028 00001
VCID: 234FE8A29B53

No fault code found.

-------------------------------------------------------------------------------
Address 19: CAN Gateway Labels: 3C0-907-530.lbl
Part No SW: 3C0 907 530 C HW: 3C0 907 951 A
Component: Gateway 007 0040 
Revision: 00007000 Serial number: 0700C06927041C
Coding: 3FFD0C04D01002
Shop #: WSC 00028 028 00001
VCID: 2143E2AA814F

2 Faults Found:
01044 - Control Module Incorrectly Coded 
000 - - 
Freeze Frame:
Fault Status: 01100000
Fault Priority: 1
Fault Frequency: 1
Reset counter: 68
Mileage: 73127 km
Time Indication: 0
Date: 2011.02.06
Time: 14:36:46

01333 - Door Control Module; Rear Left (J388) 
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 2
Fault Frequency: 1
Reset counter: 112
Mileage: 73240 km
Time Indication: 0
Date: 2011.02.07
Time: 13:17:22


-------------------------------------------------------------------------------
Address 1C: Position Sensing Labels: 1Kx-919-xxx-1C.lbl
Part No SW: 3C0 919 965 HW: 3C0 919 965 
Component: Kompass 005 0003 
Revision: 00005000 Serial number: 1166279TQWQ106
Shop #: WSC 00028 028 00001
VCID: EDDB4E9A8D17

No fault code found.

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Address 25: Immobilizer Labels: 3C0-959-433-25.lbl
Part No SW: 3C0 959 433 AK HW: 3C0 959 433 AK
Component: IMMO 051 0383 
Revision: 00051000 Serial number: VWZCZ000000000
Shop #: WSC 131071 1023 2097151
VCID: 73EFD8E26B33

Part No: 3C0 905 861 F
Component: ELV 026 0380
3C0905861F ELV 026 0380 

No fault code found.

-------------------------------------------------------------------------------
Address 42: Door Elect, Driver Labels: 1K0-959-701-MIN3.lbl
Part No SW: 1K0 959 701 P HW: 1K0 959 793 L
Component: J386 TUER-SG FT 1123 
Revision: 32008001 Serial number: 00000037169015
Coding: 0001205
Shop #: WSC 00028 028 00001
VCID: 3B7F30C203E3

No fault code found.

-------------------------------------------------------------------------------
Address 44: Steering Assist Labels: 1Kx-909-14x.lbl
Part No: 1K1 909 144 L
Component: EPS_ZFLS Kl.135 H07 1806 
Shop #: WSC 00028 028 00001
VCID: 346D1BFE2EBD

No fault code found.

-------------------------------------------------------------------------------
Address 46: Central Conv. Labels: 3C0-959-433-46.clb
Part No SW: 3C0 959 433 AK HW: 3C0 959 433 AK
Component: KSG PQ46 RDK 051 0219 
Revision: 00051000 Serial number: VWZCZ000000000
Coding: 1B910F8001860C761004141FF08A0F0E085800
Shop #: WSC 00028 028 00001
VCID: 73EFD8E26B33

Component: Sounder n.mounted 

Component: NGS n.mounted 

Component: IRUE n.mounted 

No fault code found.

-------------------------------------------------------------------------------
Address 52: Door Elect, Pass. Labels: 1K0-959-702-MIN3.lbl
Part No SW: 1K0 959 702 P HW: 1K0 959 792 L
Component: J387 TUER-SG BT 1123 
Revision: 32008001 Serial number: 00000090869012
Coding: 0001204
Shop #: WSC 00028 028 00001
VCID: 3C7D33DE06ED

No fault code found.

-------------------------------------------------------------------------------
Address 53: Parking Brake Labels: 3C0-907-801-53.lbl
Part No SW: 3C0 907 801 B HW: 3C0 907 801 B
Component: EPB VC8HC001 013 0001 
Revision: 013 
Coding: 0000013
Shop #: WSC 131071 1023 2097151
VCID: 2143E2AA814F

No fault code found.

-------------------------------------------------------------------------------
Address 56: Radio
Cannot be reached

-------------------------------------------------------------------------------
Address 62: Door, Rear Left Labels: 1K0-959-703-GEN3.lbl
Part No SW: 1K0 959 703 Q HW: 1K0 959 795 J
Component: J388 TUER-SG HL 1113 
Revision: 12005001 Serial number: 00000000754874
Coding: 0001168
Shop #: WSC 00028 028 00001
VCID: 3E7939D610F1

No fault code found.

-------------------------------------------------------------------------------
Address 65: Tire Pressure Labels: 3C0-959-433-65.lbl
Part No SW: 3C0 959 433 AK HW: 3C0 959 433 AK
Component: RDK 0440 
Revision: 00051000 Serial number: VWZCZ000000000
Coding: 0100100
Shop #: WSC 00028 028 00001
VCID: 73EFD8E26B33

No fault code found.

-------------------------------------------------------------------------------
Address 72: Door, Rear Right Labels: 1K0-959-704-GEN3.lbl
Part No SW: 1K0 959 704 Q HW: 1K0 959 794 J
Component: J389 TUER-SG HR 1113 
Revision: 12005001 Serial number: 00000000714138
Coding: 0001168
Shop #: WSC 00028 028 00001
VCID: 3F8744D217FB

No fault code found.

End ---------------------------------------------------------------------


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## Vinnyty (Mar 19, 2008)

Heres a sample of the log with the forge intake.


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## Vinnyty (Mar 19, 2008)

Here are some logs of after the stock airbox was on for a little.


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## Vinnyty (Mar 19, 2008)

So got the car back from the dealership today. Told them about the oil cap having suction. I got the car back and they said they couldnt find anything and they fixed the blower motor for the hvac. that was it.


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## lxracer (Aug 31, 2011)

Nice job with posting logs and spelling out the issue. I recently bought a Forge WINtake system and have similar problems. No P0171 code when stock, P0171 code after about 20mins of driving with the Forge WINtake.

Is there any more to this sotry? Did you ultimately resolve the issue? If so, how?


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