Car wont Start......

[rkahoi]

First off...Happy New year..
So I am Stuck with a real head scratcher.....

..03 A6 3.0L....120~k miles
Over Christmas break...I did quite alot of stuff that I've been putting off for a while...I did.
1.Bank 2 Sensor 1 02 Sensor (drivers side front)
2. Valve cover Gaskets,
3 Crankshaft Position Sensor Bank 2,
4.Because I had to get it out of the way to get to the O2 sensor, I cleaned my TB.

While putting everything back together I cracked and broke the Crankshaft breather hose...I replaced it with just a regular rubber hose, cut to fit....
All has been well for the past 3 weeks...car has been driving like a dream been getting +5-10 mpg...assuming driving with bad O2 sensors will do that..Until Yesterday...
While backing out...the car kind of shuddered..almost like it was gasping for air and then shut off...all the lights came on....MIL came on...Plugged it in.. and my logs are below...tried cranking it and motor is turning but not "catching"

4 Faults Found:
16805 - Warm Up Catalyst; Bank 1
P0421 - 001 - Efficiency Below Threshold - Intermittent
16815 - Warm Up Catalyst; Bank 2
P0431 - 001 - Efficiency Below Threshold - Intermittent
18010 - Power Supply Terminal 30
P1602 - 002 - Voltage too Low - Intermittent
18032 - MIL Request Signal Active (Check TCM for errors too!)
P1624 - 008 - - Intermittent
Readiness: 0000 0000

I was running late so took Uber to work...get home later...turn the key....car comes to life as normal....MIL is off somehow....I drive about 15mins/10~miles to a buddy's...Car was idling as I'm unloading stuff from the trunk and shudders and dies again...this time plug it in and only code that comes up is the 18010 above....I clear it...try cranking it, nothing...as I am cranking it for some reason the fan comes on a few times....and also once in a few times there's a slow whine from the secondary air pump....I sed a smoke machine to see if I have a vaccum leak and everything is ok
I have checked and rechecked my work and for the life of me I can't find anything wrong...and even if there is don't undestand whey it would drive for 3 weeks and then come up....the car is dead in the water and won't start at all...
Anybody with any ideas....?

[C5A6AVANT]

Make sure battery is fully charged lol check your connections and ground and such


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[S6XTC]

yeah my money is on either the battery has dropped a cell or bad earths/grounds.... or maybe the alternator... next time its running look for the output on vcds or just use a multi meter to see what voltage its charging at...

[rkahoi]

So I thought the same thing....I had the battery tested it checks out, the alternator was rebuilt maybe 6 months ago....the car is cranking just not catching all the way.....while trying to start it this morning scanned it and my logs are below....alot more than a few days ago but atleast it gives me something to look for or at......I'm suspecting a vacuum or something related leak since I took most of the vacuum lines off when I was doing the O2 sensor and TB cleaning....Today I'm going to retrace my steps take off everything and put it back on just to see if I missed something along the way...
Anyone know if maybe having a rubber hose instead of the plastic crankshaft hose could have any effect here....I didnt check to see if maybe they had directional valves or something...?
Hoping someone can spot something in my logs that I'm not to point me one way or another....
Thanks.

Address 08: Auto HVAC Labels: 4B0-820-043-MY2.lbl
Part No: 4B0 820 043 AM
Component: A6-Klimavollautomat 0105
Coding: 00110
Shop #: WSC 02325
VCID: 65CA71D9FF619F16E2-2580

8 Faults Found:
00779 - Outside Air Temp Sensor (G17)
30-00 - Open or Short to Plus
01274 - Air Flow Flap Positioning Motor (V71)
41-10 - Blocked or No Voltage - Intermittent
01273 - Fresh Air Blower (V2)
17-10 - Control Difference - Intermittent
00819 - High Pressure Sensor (G65)
07-10 - Signal too Low - Intermittent
01592 - Air Quality Sensor (G238)
57-00 - Electric Circuit Failure
01317 - Control Module in Instrument Cluster (J285)
49-10 - No Communications - Intermittent
01314 - Engine Control Module
49-10 - No Communications - Intermittent
01206 - Signal for Duration of Ignition Off Time
27-00 - Implausible Signal.

Address 17: Instruments Labels: 4B0-920-xxx-17.lbl
Part No: 4B0 920 981 N
Component: KOMBI+WEGFAHRS. VDO D12
Coding: 02262
Shop #: WSC 08175
VCID: 3162D589FB2903B6CE-513C
WAULT64B13N053068 AUZ7Z0B2227665

2 Faults Found:
01314 - Engine Control Module
49-10 - No Communications - Intermittent
00562 - Sensor for Oil Level/Temperature (G266)
27-10 - Implausible Signal - Intermittent

[julex]

First of all log into Engine ECU, that's the only one that matter for car to start (and cluster to get Immobilizer data)...

Sounds like ground issue to me... Too many electrical incommunicados in there. Check for melted O2 wires since you remarked that you were wokring on O2 sensor. If it is touching the exhaust anywhere, it will melt and cause short... sometimes it might kill the ECU too which might be what you see. It will crank without ECU but it will not catch, and ECU will not respond to VCDS access. Check fuses (especially for ECU which there are several of).

Edit: And reset all codes too and see what comes back after an engine cranking session.

[rkahoi]

So I re-traced my steps pulled and put everything back together......car still wouldn't start....decided to pull spark plugs....and found the fuel soaked...so somehow engine had flooded...so left it to dry out...put them back in and voila...car started and ran fine for a 3 days or so....and then on the 4th day, same thing.....crank no start..., pulled plugs again...this time plugs weren't as soaked...but were moist...left them out for a few hrs...put them back in and been driving it for the past week...I'm just waiting for the next time it happens now....I cleared my codes and these are what's pulling up now..

Address 01: Engine Labels: 06C-909-559-ASN.lbl
Control Module Part Number: 8E0 909 559 E HW: 8E0 909 059
Component and/or Version: 3.0L V6/5V G 0003
Software Coding: 0016752
Work Shop Code: WSC 02325 785 00200
VCID: 3776EB91454DDD8680-515A
6 Faults Found:

18057 - Powertrain Data Bus
P1649 - 008 - Missing Message from ABS Controller - Intermittent
18010 - Power Supply Terminal 30
P1602 - 002 - Voltage too Low - Intermittent
16825 - EVAP Emission Control Sys
P0441 - 002 - Incorrect Flow - Intermittent - MIL ON
18032 - MIL Request Signal Active (Check TCM for errors too!)
P1624 - 008 -
16805 - Warm Up Catalyst; Bank 1
P0421 - 001 - Efficiency Below Threshold - MIL ON
16815 - Warm Up Catalyst; Bank 2
P0431 - 001 - Efficiency Below Threshold - MIL ON

Readiness: 0000 0000

....nothing to point me to one direction or the other...so...
Is it possible that my injectors are failing/failed....and how would I even test for this...?
Is there a way to test fuel pressure...I'm suspecting also maybe a fuel pump/ fuel filter...because I noticed everytime this has happened my tank has been at or just under 1/4...
Any more Ideas...?

[Evilgoat76]

Any codes in Transmission ECU as the engine ECU is indicating this may be the case. Check everything on the bulkhead is connected right and maybe some contact cleaner in there