mtnboydl

Hey guys- Thought I would start a new thread to get your thoughts rather than piggyback off of a previous post of mine.

In the sig, but 2012 A8 with 4.2. 75k miles

Had some issues pop up a few weeks ago during a long road trip, about 300 miles in. Big temp drop outside, down to 0 deg F, which may have some to do with the issues starting? Several codes popped up at once (see below), and a squealing noise that was corrected with PCV replacement.

Now on another road trip, around 300 miles into the trip, CEL comes back on. No running issues, no rough idle, etc.

My inkling is a vacuum leak somewhere, but not sure the best way to find the leak. My childhood experiences involved spraying carb cleaner along a small handful of hoses to find the leak. Less possible with all of the lines on newer engines.

Codes from pre-PCV 2wks ago
01 Engine

System description: 4.2l V8/4V
Software number: 4H0907560C
Software version: 0006
Hardware number: 4H0907560
Hardware version: H07
ODX name: EV_ECM42FSI0114H0907560C
ODX version: 001007
Long coding: 0106000A290F0268

Trouble codes:
P209800 - Post Catalyst Fuel Trim System Bank 2 Too Lean
Intermittent
Date: 2018-01-04 18:21:48
Mileage: 121261 km
Priority: 2
Malfunction frequency counter: 3
Unlearning counter: 255
Engine speed: 1695.00 1/min
Normed load value: 44.7 %
Vehicle speed: 100 km/h
Coolant temperature: 99 °C
Intake air temperature: 5 °C
Ambient air pressure: 980 mbar
Voltage terminal 30: 13.853 V
Dynamic environmental data: 209628100C044F110B000005C711280610FC06BB11123B10F4 23651016086D
P227900 - Intake Air System Leak
Intermittent
Date: 2018-01-05 11:39:26
Mileage: 121802 km
Priority: 2
Malfunction frequency counter: 3
Unlearning counter: 255
Engine speed: 659.00 1/min
Normed load value: 24.7 %
Vehicle speed: 0 km/h
Coolant temperature: 80 °C
Intake air temperature: 26 °C
Ambient air pressure: 970 mbar
Voltage terminal 30: 14.135 V
Dynamic environmental data: 209628100C00CE110B000007EA11280510FC033911123410F4 121510160277
P045600 - EVAP Emission Contr. Sys. (very small Leak) Leak Detected
Intermittent
P017400 - Fuel Trim,Bank2 System too Lean
Intermittent
P017100 - Fuel Trim,Bank1 System too Lean
Intermittent

Codes yesterday after PCV replacement:
01 Engine

System description: 4.2l V8/4V
Software number: 4H0907560C
Software version: 0006
Hardware number: 4H0907560
Hardware version: H07
ODX name: EV_ECM42FSI0114H0907560C
ODX version: 001007
Long coding: 0106000A290F0268

Trouble codes:
P209800 - Post Catalyst Fuel Trim System Bank 2 Too Lean
static
P045600 - EVAP Emission Contr. Sys. (very small Leak) Leak Detected
static

Looking forward to hearing your thoughts (including the guardian angel of this forum MP4.2+6.0)

mtnboydl

Any thoughts from you all?

spdemon91

Just got first CEL on my 2013 S8... Threw the same code as yours P209800 plus code P14AB00. I see you didn't get any responses from the community but curious to know the outcome of your issue. Also, anyone in the Audi world have experiences with these CEL codes who can shed light on them would be much appreciated.

yuvalw123

some times it can be a simple thing like not closing good the gas cup.
however in the D3 the cell light can go away , but with the D4 , the cell light must be reset with scanner. ( I had a D3 and have a D4 now )
for now , clear the code and see what happen. if its coming back , it can be annoying to find the leak.
good luck

MP4.2+6.0

Most likely guess would come right from the text of your original post. Thus, look around the whole area where you replaced the PCV valve. Also, if by chance you used aftermarket, aka a "cheap" one, could be you got cheap in more ways than one. PCV valve dumps into intake, so it has to seal and function correctly. At cold start, PCV is also dealing with water vapor in crankcase, so your text about it being cold is sort of another clue there. If the vapor somehow froze up in the critical areas of the PCV valve, it could lead to the issue. Unlikely in OE/dealer part. More likely if aftermarket poorly implemented copy.

I don't know D4 4.2, but besides PCV area re-inspection, D3 port version leaks would often be to the combi[nation] valves that were vacuum driven (passenger side in back of motor, drivers was in front IIRC) or to the intake runner vacuum pods that actuated them--front of motor in the "V" area. At least the latter may have changed with FSI.