2009 A6 3.0T VCDS Scan Reveals Massive Fault List, Battery Drain, and Refuel Issue

[andrewrico]

Hey everyone,

Hoping someone here can help me piece together what’s going on with my 2009 Audi A6 Quattro 3.0T. I ran a full VCDS autoscan and pulled 66 fault codes (yes, seriously). A few of them are recurring or seem interconnected, and I’m trying to figure out what’s actually critical vs. noise.

Here’s what I’m experiencing:

Car starts fine normally, but after not driving for 2–3 days, the new battery dies

Post-refueling, the car sometimes cranks long or won’t start unless I give it time or pump the gas

Already replaced the purge valve (N80) with a brand-new one — no change

Intake manifold codes showed up: P200A, P2006, P2007

EVAP codes: P0441, P0455

Multiple under-voltage and power supply-related errors: 00532, 00446 (x3), 02252 (Generator), 02256 (Battery Drain)

VCDS also reports:

Airbag module checksum errors

Quiescent current exceeded

Component protection active in several modules

Tire pressure and door lock faults

It feels like a mix of EVAP issues, possible alternator/ground faults, and maybe some leftover crash or retrofit coding issues.

Any help on what to tackle first, or common culprits you’ve seen on this platform?

Below is the full VCDS Scan. Appreciate any insight!


– Andrew

[andrewrico]

https://drive.google.com/file/d/14E5...ew?usp=sharing

This is the VCDS scan having some trouble adding attachments directly to Audizine

[jbain2]

You can also cut and paste the scan into your post. I’m assuming you have cleared the codes and seen what comes back?


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[Avantly]

I can't see the google post for some reason, but with this many codes you likely have a root cause that is only one or two points of failure.

First step you need to take is make sure the battery is still in good condition (completely discharging a non-deep cycle lead chemistry battery can damage it almost immediately), clear the codes, drive it, scan it again and see which codes persist. This will give you a better hint as to what's going on.

The first question I'll probably ask will be when was the last time you checked/cleaned the cowl drains. It's common for modules on the MOST ring to throw CP errors during low battery events (Bose amp, MMI head, etc). The airbag module checksum error is interesting, haven't seen that one before but could possibly be caused by low/unstable voltage due to high battery impedance from discharge damage.

There is a common issue with C6 where the wire harness in the flexible rubber tube between the pillar and the door develops cracks in the wire insulation and shorts, I have had that problem on all of my C6. Usually causes door faults and significant CAN bus communication issues.

Water in the drivers side floor from cowl leak will kill bluetooth module which will knock out MOST ring, but this usually causes the MMI screen to be blank.

Can you be more specific about driving it 2-3 days and the battery dying? Does it die while parked, or is it just dead after driving 2-3 days? There is a battery control module against the rear side of the spare wheel well which suffers water damage, usually on the avants, from leaks into the brake lights. Water related corrosion to that module or its connector will cause the battery light to come on and failure to charge (fails to command charging voltage from alternator).

Try charging battery, verifying it's good (cranks normally, not slowly), clearing codes, driving, and scanning again then post results.

[andrewrico]

Thanks for the detailed reply — really appreciate it.

To clarify, the battery is brand new (installed about 2 weeks ago), and the car starts strong when driven daily. But if it sits parked for 2–3 days, the battery is completely dead and requires a jump. After that, it drives fine again.

I haven’t checked the cowl drains yet, but I will — makes sense if water intrusion is affecting wiring or modules. No visible signs of wet carpet or moisture inside though. I’ll also inspect the door harness rubber tube — sounds like a likely candidate since I have a bunch of door module faults and window/lock issues.

As for the airbag checksum error: yeah, that one worried me too. Could be past crash damage (I suspect the car had an accident at some point based on the module behavior and CP errors).

I’ll charge the battery fully again, clear all codes, drive it, and re-scan like you suggested. I’ll follow up here with the fresh results.

Thanks again for the guidance!

I've also included below the VCDS Scan since the printout was 14 pages long I condensed it to include the codes only let me know if you'd like the full scan I would have to email it at that point.

Engine (01)
P0441 – EVAP Emission Control System Incorrect Flow

P0455 – EVAP System: Large Leak Detected (Intermittent)

P200A – Intake Manifold Flap (Bank 1) Malfunction

P2006 – Intake Manifold Flap (Bank 1) Stuck Closed

P2007 – Intake Manifold Flap (Bank 2) Stuck Closed

U1008 – Check DTC Memory in CAN Gateway (Intermittent)

ABS Brakes (03)
01826 – Steering Angle Sensor (G85): Supply Voltage Terminal 30 (Intermittent)

Access/Start Authorization (05)
00446 – Function Limitation due to Under-Voltage (Intermittent)

Auto HVAC (08)
00715 – Rear Footwell Vent Positioning Motor Mechanical Failure

01232 – A/C Compressor Regulator Valve: Open or Short to Plus

00256 – A/C Pressure/Temp Sensor: Lower Limit Exceeded

00739 – Coolant Circulation Pump: Upper Limit Exceeded

Central Electronics (09)
01494 – Bulb for Parking Lamps Left (Open Circuit)

Airbags (15)
26 separate airbag/control module faults, mostly:

B100A–B1025 – Igniter-related: Short to Plus or Resistance Too High

B2000–B2000 94 – Internal Control Module Memory Errors

U1011/U1012 – Voltage too Low/High

B1022 – Seat Occupied Recognition Signal Implausible

Steering Wheel (16)
00446 – Function Limitation due to Under-Voltage

00532 – Supply Voltage B+ Lower Limit Exceeded (Intermittent)

CAN Gateway (19)
02252 – Generator: No Signal

02095 – Component Protection Active

00384 – Optical Databus Open Circuit

02256 – Quiescent Current: Upper Limit Exceeded

03041 – Energy Management Active

Seat Memory Driver (36)
03332 – Height Adjustment Motor: No/Incorrect Basic Setting

03333 – Cushion Angle Motor: No/Incorrect Basic Setting

02095 – Component Protection Active

03316 – Cushion Angle Sensor: Implausible Signal

03323 – Fore/Aft Adjustment Switch: Mechanical Failure

Driver Door (42)
00446 – Function Limitation due to Under-Voltage

Central Convenience (46)
01504 – License Plate Bulb: Open or Short to Ground

01134 – Alarm Horn: Electrical Fault

01696 – Rear Left Footwell Lighting: Open Circuit

Tire Pressure (4C)
02214 – Tire Pressure Warning

01316 – ABS Control Module: Check DTC Memory

00778 – Steering Angle Sensor: Check DTC Memory

03542 – Wheel Diameter Implausible

Passenger Door (52)
02115 – Central Locking: Implausible Signal

00446 – Function Limitation due to Under-Voltage

Parking Brake (53)
01321 – Airbag Control Module: Check DTC Memory

Rear Left Door (62)
02110 – Window Regulator Switch: Implausible Signal

02115 – Central Locking: Implausible Signal

02111 – Window Regulator Motor: Open Circuit

Rear Right Door (72)
02115 – Central Locking: Implausible Signal (Intermittent)

[jbain2]

A couple of thoughts. I’d clear the codes. Then do some driving and re-scan. See what comes back. Many of those are voltage related issues that arise when the battery is either dead or removed.

I suspect you have an evap vapor lock issue that’s causing your starting issues after fueling.


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[andrewrico]

Thanks for the reply, that makes sense. I’ll go ahead and clear everything and see what comes back after a few drives. A lot of the codes do seem to be triggered by the low voltage situation, so hopefully that trims it down.

Interesting call on the vapor lock. I hadn’t considered that, especially since I already swapped the purge valve (N80) with no change. Is there anything else in the EVAP system you'd recommend checking that might contribute to vapor lock? Like the vent line, charcoal canister, or fuel tank pressure sensor?

Appreciate the input!

[Avantly]

Definitely do what jbain2 said, and get a full scan without battery voltage getting low. There are quite a few codes in there (including the steering angle related codes) which are simply going to be the result of low battery voltage.

Once you do that, we can see which codes come back right away after clearing them, and which ones are very intermittent or related to the low voltage.

[jbain2]

The evap system is extensive. Many items from the charcoal canister in the tank all the way up to the engine bay. In my experience the best way to look for evap leaks/issues is by doing a smoke test. Checking and replacing the purge valve
Like you have done is often a common culprit. Charcoal canister is also a common failure point.


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[andrewrico]

Hi guys thank you so much for your inputs I'm going to reset the codes and drive a little bit. I managed to get the drive link to work too if you guys want to have a look at the VCDS scan. Thanks!

https://drive.google.com/file/d/14E5...ew?usp=sharing