Update -

Thanks for the suggestions and empathy...

Auto Zone ran a Audi scope and came up with a Code #P1136. Their print-out didn't list the Audi A-4 as a car option, but under Volkswagen included...

Definition:
Long Term Fuel Trim Add. Fuel B1 System Too Lean

Explanation:
Failed MAF

Probably Causes:
Low Fuel Pressure
Vacuum Leak on Engine
Failed HO2S

Still could use some suggestions from thoughtful forum members...

And from earlier post...

HELP!

1999 A4 1.8T 5 Spd. Quattro 120k

CEL [Snap-on Scope] #1136

Confounding problem started with CEL and engine wouldn't hold basic idle after filling tank. After manually keeping revs up and driving for a few minutes, standard 900 rpm idle settles in and runs like a clock until next tank of gas.

That was 3 Months and several thousand $'s ago. My favorite [and usually very good] mechanic is now quite stumped and I am out of dough.

Replaced thus far:

Fuel Filter
Mass Air Flow Filter
Turbo
Fuel Pump

Car runs a bit better overall [thanks to a bunch of brand new parts], but initial symptoms still in play...

Any thoughts and suggestions would be greatly appreciated...even someone with a Audi-specific scope who can help translate Snap-on Codes to Audi Codes? Is that even possible?

A good ride that is teasing me right now...

Wrecker Out

 

Screw the snap-on codes. Just go to AutoZone and have your ECU scanned for free. Don't necessarily trust the definition of the code that they give you though - bring the codes home and post them here and search them out on here. I had a code for a bad passenger side cam sensor, and it told me it was a driveability error - maybe not incorrect, but not really correct either. Have the car scanned there, search your code here, and you should find what you need.

 

I bet it's a $20 part.
This is what I hate today, no one knows how to diagnose or do hands on check on things, they just read a code & throw money at it.

I would test & replace the coolant temp sensor.

Why did you replace the turbo? Tell you tech to purchase a $250 Vag-com if he wants to work on Audi's!

 

2006 Audi A 3 2.0 T

Code: P0171

Definition: System too lean- bank 1 (Cylinder number 1 denotes bank 1)

Explanation: Low fuel pressure or volume

Probable cause # 1: Faulty H02S (heated oxygen sensor)
# 2: Large vacuum leak
# 3: Faulty MAF sensor

Just took the A-3 to the dealership yesterday and paid about $700.00 for a vacuum leak.
Coming back from the market an hour ago the engine light came back on.
The code above is from Auto Zone 30 mins. ago.

Any suggestions, clues ?
Thanks !
ldv-r

 

First thing I'd check is the crankcase pressure regulating valve (pcv) on the left side of the valve cover. They are a common failure. Also, SOME have a check valve in the pipe that goes from the valve cover to the turbo. If it comes apart, it'll be lean. Have to be sure the correct p/n pieces are used. There's 2 different ones and they aren't interchangeable.

Another common cause is the high pressure fuel pump. Actually it's the tri-lobe on the camshaft wearing and then the follower. If it gets bad enough it wears the end of the pump push rod off. At first, it will mainly cause a P0171 lean fault.

If neither of those have been checked or replaced, start there. One check is to idle the engine and see if you can take the oil fill cap off. There should be a SLIGHT vacuum but if you need two hands to pull it off, the crankcase pressure regulating valve is the problem.

Also a good idea (if no faults are found), hook up a fuel pressure gauge and a scanner. Monitor the low pressure (from the tank) with the gauge and high pressure with the scanner (there's a high pressure fuel sensor). Compare them with specs.

As mentioned here, never rely on Auto Zone for a "diagnosis". Code reading, yes. A fault code means nothing other than a place to start the diagnosis. A P0171 is almost NEVER caused by a faulty O2 sensor, and rarely does a MAF sensor fail either and cause only a P0171. It can but, most times not. I'm an auto tech (and former Audi stealership tech) and HATE "parts replacers". Gives us all a bad name.

 

Thanks for the info, it's great !

I've look for the pcv on rockauto.com and audiusaparts.com and can't find it, so I can order it. Rockauto as a part that looks like a tubing (flexible), like the one in the engine.
Again thanks,

ldvr