1997 Audi B5 A4 2.8L V6 12V (AFC)

   #1  

o2bad455

Verified VCDS User
Verified
Joined
Feb 7, 2023
Messages
11
Reaction score
4
Location
North America
VCDS Serial number
C?ID=11368
There's an issue with the VCDS codes. The car is No Start. The timing belt is good and properly aligned. Here's the engine scan:

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


Address 01: Engine Labels: 8D0-906-266.lbl
Control Module Part Number: 8D0 906 266 B
Component and/or Version: 2,8l V6/2V MPI OBD2 D02
Software Coding: 01201
Work Shop Code: WSC 06325
VCID: AB5F18F559F07ED587-515A
2 Faults Found:

17748 - Camshaft Position Sensor (G40) / Engine Speed Sensor (G28)
P1340 - 92-00 - Incor. Correlation
17800 - Camshaft Position Sensor Bank 2 (G163)
P1392 - 92-00 - Open Short to Plus

Readiness: N/A

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

Although these codes reference TWO different CAM position sensors and ONE ESS CRANK sensor, I think these 12V engines have only ONE CAM sensor but TWO CRANK sensors. In any case, this particular 12V AFC engine only has just one cam sensor (G40 Hall-effect cam sensor located at rear of left bank). I know there's another G163 CAM sensor on the 1998-up 30V engines, but it seems to be absent from the 1997-down 12V engines. See 12V.org. So what should the second code for "G163" mean?

I'd assumed it must have meant G40 instead of G163, but after testing the G40 wiring and then replacing the G40 sensor, it's still no start and spitting up exactly the same codes. Could the G163 be referring to some other sensor? The two CRANK sensors are a G4 at one of the crank throws and a G28 at the flywheel.
 
Last edited:
   #2  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
473
Reaction score
272
Location
UK
VCDS Serial number
C?ID=6386
Has been a long time since I was upside an old B5 V6 motor but my memory is there are two camshaft (hall effect) sensors - G40 and G163. Those inform the ECU the correct phase of the engine for ignition etc. At the crank you have G28 for the engine rpm sensor and that may incorporate a special tooth pattern such as 60-2 or 36-1 so the ECU can establish the crankshaft position unless it has a separate crank position sensor (G4) like the mighty old 5 cyl motor.

What I am seeing for P1340 is incorrect correlation of G40 / G28 - that can mean your mechanical timing has slipped such that the G40 signal is occurring at a time which is inconsistent with where the ECU expects it to be - if the ECU cannot establish sync there is no point in it trying to inject fuel or ignite it. Other less dramatic causes could be faulty G40 sensor or bad wiring.

For the P1392 code that points to a faulty sensor or wiring as well - on the other bank for G163.

With a voltmeter, check for presence of a clean 5V supply to both camshaft sensors - I would have to look at the WD for pin numbers. If you have access to an oscilloscope you should see each camshaft sensor supply a 5V signal at the other pin and the period when the G40 signal is 0V should coincide with the G28 (or G4) crank reference signal IIRC.
 
   #3  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
473
Reaction score
272
Location
UK
VCDS Serial number
C?ID=6386
Looking at AAH & ABC schematics (older 12V engines) they only have the one camshaft sensor (G40) - you should see 5V across pins 1 & 3 and the 'hall effect window' signal at pin 2 vs 0V. Those engines did have separate G4 and G28 sensors but I cannot yet track down a WD for the AFC motor - its not in my personal collection yet.
 
   #4  

o2bad455

Verified VCDS User
Verified
Joined
Feb 7, 2023
Messages
11
Reaction score
4
Location
North America
VCDS Serial number
C?ID=11368
   #5  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
473
Reaction score
272
Location
UK
VCDS Serial number
C?ID=6386
The only chance of getting that WD for the AFC engine is via ERWIN site. I have a suspicion it may be a US only motor as I cannot find it referenced across a quick look of PL24 in Europe. There is a chance it appeared on the A8 - have not checked that.
 
   #6  

ryvrgc

Verified VCDS User
Verified
Joined
Oct 6, 2019
Messages
3
Reaction score
0
Location
Canada
VCDS Serial number
C?ID=381442
The AFC model in Canada was in 1997 A4 Quattro's.

This document might help you??

Self Study Program
Course Number 841003

It contains Motronic 5.9 ECU components and systems.

SSP 840293 has other Motronic's 7+

(edit) page 112 of SSP 841003 for Motronic 5.9.2 explains two sensors: sensor 1 cyl 1-2-3 G163 is located on passenger's side of engine, sensor 2 cyl 4-5-6 G40 is located on driver's side rear of the engine
 
Last edited:
   #7  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
473
Reaction score
272
Location
UK
VCDS Serial number
C?ID=6386
The AFC model in Canada was in 1997 A4 Quattro's.

This document might help you??

Self Study Program
Course Number 841003

It contains Motronic 5.9 ECU components and systems.

SSP 840293 has other Motronic 7+
Good find, but its the WD that is needed really - probably only accessible via Erwin USA/CAN site.
 
   #8  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
473
Reaction score
272
Location
UK
VCDS Serial number
C?ID=6386
(edit) page 112 of SSP 841003 for Motronic 5.9.2 explains two sensors: sensor 1 cyl 1-2-3 G163 is located on passenger's side of engine, sensor 2 cyl 4-5-6 G40 is located on driver's side rear of the engine
Best practice is to avoid 'driver side' and 'passenger side' when talking about location of engine components (or anything generally car related IMHO on a global forum).

Bank 1 = right side
Bank 2 = left side

The sense of left & right is determined by sitting in the car looking in a forward direction.
 
  • Like
Reactions: Uwe
   #9  

o2bad455

Verified VCDS User
Verified
Joined
Feb 7, 2023
Messages
11
Reaction score
4
Location
North America
VCDS Serial number
C?ID=11368
The AFC model in Canada was in 1997 A4 Quattro's.

This document might help you??

Self Study Program
Course Number 841003

It contains Motronic 5.9 ECU components and systems.

SSP 840293 has other Motronic's 7+

(edit) page 112 of SSP 841003 for Motronic 5.9.2 explains two sensors: sensor 1 cyl 1-2-3 G163 is located on passenger's side of engine, sensor 2 cyl 4-5-6 G40 is located on driver's side rear of the engine
Thanks, that's interesting if Canada got a newer gen ECU for the AFC than the States (usually the opposite), but mine is definitely a States car and I'm afraid p.112 is referring to a 2.8L 30V since it says the 2 cam sensors are on the two "intake" cams and only the 30V has separate intake cams. It also mentions Passat and I think those all had 1.8L 20V or 2.8L 30V, FWIW. I'm pretty sure at least the States version 1997 A4Q 2.8L 12V AFC still has just one cam per bank, left with cam sensor and right without. I guess VAG probably calls the cam sensor G40 instead of G163 since there's just one, regardless of L/R side. My control module is 8D0 906 266B.
 
Last edited:
   #10  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
473
Reaction score
272
Location
UK
VCDS Serial number
C?ID=6386
You have both G40 and G163 - normal practice for a V6 engine - even one from that era. Borrow an oscilloscope and probe G40, G163 and G28 while cranking - then you will see if the signals correlate... and/or tear enough of the engine down to visually check the mechanical alignment between crankshaft & camshaft - I expect that will be a toothed timing belt on that engine.
 
   #11  

o2bad455

Verified VCDS User
Verified
Joined
Feb 7, 2023
Messages
11
Reaction score
4
Location
North America
VCDS Serial number
C?ID=11368
You have both G40 and G163 - normal practice for a V6 engine - even one from that era. Borrow an oscilloscope and probe G40, G163 and G28 while cranking - then you will see if the signals correlate... and/or tear enough of the engine down to visually check the mechanical alignment between crankshaft & camshaft - I expect that will be a toothed timing belt on that engine.
Are you sure? This is a USA model year 1997 2.8L 12V A4Q with AFC engine code. The door-jamb production date is 10/96. I still can't find a G163 or second cam sensor to test, nor its harness connector. This engine only has one left bank camshaft and one right bank camshaft. ETKA only lists the one Hall effect cam sensor that's called G40 and mounted at the rear of the left bank. See 12V.org. I inspected the rear of the right bank and there's no sensor whatsoever. I tore into the right bank this weekend so I'm now 99.9% sure that there's no cam sensor at all on that bank. Replaced the timing belt for good measure. I can't imagine why they'd put two cam sensors on the same cam for the left bank, but didin't see any sign of a second one there either. To be clear, the only cam sensor that I've found, and replaced, was the one at the rear of the left bank (US driver's side). It has 11V between pins 1 and 3, where the Bentley manual specifies at least 9V. I spotted and replaced a partially melted 20A fuse #29, but still no spark. Don't have access to an oscilloscope, but might buy one if I can find something sturdy.

Could this second code that says G163 actually mean G40 (the Hall cam sensor at rear of left bank, just like the first code that does say G40), or could it refer to the G28 engine speed flywheel sensor, or is there really another cam sensor hidden somewhere that I've repeatedly missed? Also, isn't "bank 2" normally the left? But in this case the G40 is on the left, so would that put G163 on the right bank?

17800 - Camshaft Position Sensor Bank 2 (G163)
P1392 - 92-00 - Open Short to Plus
 
Last edited:
   #12  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
473
Reaction score
272
Location
UK
VCDS Serial number
C?ID=6386
Some thoughts...

1 - the old 12V.org site does not cover anything significant for engine electrics on the AFC engine - well I could not see anything on it anyway in a quick look

2 - your fault code 17800 explicitly calls out camshaft sensor for bank 2 and references G163 for that - potentially that could be a red herring called up by VCDS if whatever error code coming from the ECU is referencing

3 - if G163 and G40 are indeed hall effect sensors on the AFC motor then they will have 5V operation - at least thats all I have ever encountered in respect to hall effect sensors. Its one of the reasons we have +5V reference voltages on these wonderful ECUs for things like hall effect sensors and other environmental sensors. Would be very weird to have a 9V reference on a 1997 engine IMHO.

4 - you need to not continue assuming this motor is same as AAH (its not) and spend a fistful of dollars on the factory manual and WD for this generally rare engine - yes it will have some aspects very much like the AAH predecessor, but not exactly the same.

5 - G28 is an engine rpm sensor on the crankshaft. In older engines like AAH there was also G4 for crank position, but they may have been deleted on the AFC if they moved to a more modern design where a gap in a 36-1 or 60-2 toothed flywheel provides the ECU with the crankshaft reference position using G28 without G4.

6 - If you have no signal from G28 (or G4), or both of G40 & G163 are out of the sync window (or dont exist) then the ECU will not generate spark as it will have no clue 'where' the engine is in its four stroke cycle.

7 - You typically need a minimum rpm speed or around 20rpm detected on G28 to activate the fuel pump as well

8 - Ever considered that whatever caused Fuse 29 to melt has caused some wiring damage along the way ?

9 - Right = Bank 1, Left = Bank 2. End of.
 
Last edited:
  • Like
Reactions: Uwe
   #13  

o2bad455

Verified VCDS User
Verified
Joined
Feb 7, 2023
Messages
11
Reaction score
4
Location
North America
VCDS Serial number
C?ID=11368
Much appreciated, Thank you!

1. I stand corrected! According to ETKA 7, the 2.8L 12V code AFC engine came in the 1995 Audi 80/90Q for USA as well as the 1996-1997 Audi A4 for USA, but it looks like 2.8L 12V code AAH came in 1993-1994 80/90Q for USA. 12v.org has a great ECU wiring diagram for mms300, but I think you're right that it's not applicable to AFC. I guess it's just for AAH. Thanks!

2. Agreed.

3. It's confusing and I'd originally read the "9V" online, but now I have the hardcopy Audi A4 Service Manual 1996-2001 from Bentley Publishers, and it also says "Specified value: min. 9 volts" at page K28-13. Only one cam sensor is mentioned in this diagnostic portion of the manual. The only thing I can say for sure is that I measured mine at 11V, which seems like a highly unlikely failure mode if it were actually supposed to be 5V.

4. I've now got the Bentley manual as mentioned above, thanks! The A4 Bentley breaks down AFC engine management into 1996 model year, and separately 1997 model year. For 1997 m.y., there also seem to be some differences for 10/96 versus 5/97 production (i.e., a mid-year change) as well as for manual versus automatic (mine's got the 5-speed manual trans). My chassis was made 10/96 so I'll go with that, and I've confirmed that my ECU has the "B" suffix (USA?). VERY INTERESTINGLY, the '96 has just one cam sensor (G40) per Bentley page Y27 and Y53 (wiring diagram 1/4) connected to ECU pins A2 and B2, while at least some of the 1997 (not sure yet if 10/96-on or 5/97-on) may supposedly have two cam sensors (a G40 and a G163) per Bentley page Y29 and X(?)/Y144 (wiring diagram 21/7) connected to ECU pins 76, 11 and 44 (very odd numbering because I remember the ECU pinout by connector letter as per 1996 m.y., but perhaps Audi renumbered from the 1996 to the 1997 ECU even though they have the same part numbers; and also the later 30V AHA has exactly the same cam sensor pinout at page Y226). However, the fact remains that I haven't located any sign of the second cam sensor or it's wiring on my particular AFC engine. I'll try to check at least the ECU end of the purported first and second cam sensor wires with the DMM next weekend (e.g., see if it's populated, check continuity to ground and/or positive, etc.).

5. Yes, this 1997 AFC also has a G4. I'd actually tried replacing the G4 sensor with a new one (no suffix for the G4 CPS versus "A" suffix for the G28 ESS), but no difference and now back to original so as not to introduce any more variables.

6. As a sanity check, I'll verify signal existence from all three sensors this weekend with my trusty DMM or an LED test light, and if all talking then potentially get an oscilloscope to further investigate sync window (if I can find actual specs for it somewhere - possibly in the Bentley although I haven't spotted it yet).

7. Yes, I believe I'd read 29 RPM for G28 somewhere in the Bentley, and I recall it saying that's not obtainable with just the starter. No good enough hills nearby, although I suppose a pull start could achieve it if needed. The fuel pump relay on this car also seems to operate momentarily upon each start cycle since I hear the pump momentarily. So the underlying issue seems to be causing no spark rather than no fuel.

8. Sure did. It was 20A fuse 29 (not 15A fuse 28, which from memory might have been for the fuel pump). After replacing it, no melting issue so far but I sure was curious. I combed through half a dozen interrelated wiring diagram pages in the Bentley last night, and fuse 29 appears to be related to a primary O2 sensor heater (not sure if left or right bank). There could be an issue there, but I'd assume that shouldn't be enough reason to completely block spark. That said, if nothing else turns up I might try insepcting the O2 sensor wiring for damage, etc.

9. Got it, thanks!
 
Last edited:
  • Like
Reactions: Uwe
   #14  

o2bad455

Verified VCDS User
Verified
Joined
Feb 7, 2023
Messages
11
Reaction score
4
Location
North America
VCDS Serial number
C?ID=11368
Just to clarify, how does VCDS differentiate G40 and G163 for engines that do have both? Iif just one, is it always called G40 regardless of location (e.g., right bank #1 or left bank #2)? On this '95-'97 AFC 12V engine, the Hall-effect cam sensor at the rear of the left bank #2 is called G40 by Audi. But IIRC, on the 30V the one they call G40 is actually on the front of right bank #1 while the one they call G163 is on the rear of left bank #2. Is this a source of confusion?

On my '97 AFC 12V engine, there is no cam sensor at the back of right bank #1. I even took a picture, but can't upload here since not hosted. Unlike the 30V which has the second cam driven by internal chain so the right bank #1 can have a cam sensor at the front where not blocked by a cogged belt pulley, there's no place for a cam sensor at the front of either bank on the AFC since the only two camshafts each have cogged belt pulleys at the fronts.
 
Last edited:
   #15  

Uwe

Benevolent Dictator
Administrator
Joined
Jan 29, 2014
Messages
53,815
Reaction score
36,363
Location
USA
VCDS Serial number
HC100001
Just to clarify, how does VCDS differentiate G40 and G163 for engines that do have both?
It's just based on the text that VAG defined for the respective fault codes way back when.

-Uwe-
 
   #16  

stefdds

Verified VCDS User
Verified
Joined
Apr 13, 2015
Messages
3,089
Reaction score
2,326
Location
Milwaukee, Wisconsin USA
VCDS Serial number
C?ID=174556
I even took a picture, but can't upload here since not hosted


 
  • Like
Reactions: Uwe
   #17  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
473
Reaction score
272
Location
UK
VCDS Serial number
C?ID=6386
There are a few possibilities here...

1 - VCDS is giving a bum steer towards G163 if your engine really doesn't have one - and that may be because the info supplied by VAG was incorrect or incomplete. Your suggestion that VCDS is referencing G163 as the only camshaft position sensor when logically (in my mind at least) G40 would be the primary one and G163 the secondary.

2 - Could the engine mechanically be the early AFC variant with a single cam sensor (G40) while the ECU software is from the later variant that expects to see both G40 and G163 - has it only recently developed this no start fault or have you inherited the car with no history.

3 - If you can share your VIN number we can work it when it was manufactured and cross-check ECU part numbers and other stuff.

Meanwhile - funny story... Just remembered that I have some old Bentley manuals in the library including the correct one for B5 A4 with the AFC motor so let me have a proper look and acquaint myself with that.
 
   #18  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
473
Reaction score
272
Location
UK
VCDS Serial number
C?ID=6386
Right so the early AFC only has G40 (CMP-1) while later AFC has G40 & G163 (CMP-2) - wiring differences are clear to see and now I see the cause of confusion here. Referencing Section Z in the Bentley manual we have :

17748 : Crankshaft / camshaft position signals out of sequence
17800 : Camshaft position sensor Bank 2, Open Circuit / Short to B+

What I think is happening is that VCDS is seeing the reference to Bank 2 for the 17800 fault code and suggesting that relates to G163 when in fact there is only the one CMP sensor on the motor (G40) and it is on Bank 2 as shown in Bentley manual for the early AFC engine on page K-24-3 item number 27.

Bizarrely I can only see G40 & G163 on the schematics for the later AFC (page Y144) but no mention made of it in the mechanical section. Meanwhile the early AFC schematic shows G40 on page Y53.

So lets verify the P/N of your ECU and the number of pins/connectors so we can confirm its the early AFC engine.

You are right about the CMP sensor(s) on this engine working from nominal 12V supply across pins 1 and 3 - this flavour of ECU is not using 5V logic for that so apologies for that bum steer.
 
   #19  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
473
Reaction score
272
Location
UK
VCDS Serial number
C?ID=6386
Then you will need an oscilloscope to see what signals G4, G28 and G40 look like. I am expecting the window of G40 to encapsulate the crank reference signal pulse from G4. Both G4 and G28 are inductive sensors.
 
   #20  

o2bad455

Verified VCDS User
Verified
Joined
Feb 7, 2023
Messages
11
Reaction score
4
Location
North America
VCDS Serial number
C?ID=11368
I'll PM you the VIN. The car's been in the family since 2010 or so. It had been sitting unused during Covid, but fired right up last fall and I drove it 1/4 mile or so with no running issues. When I came back a month or so later, the AC compressor had seized so I had to remove the belt to let it start again. Ordered the shorter non-AC belt, but it was no-start due to no spark when I came back another month or so later. Although I've swapped many bits in and out for testing, the only permanent changes since the issue began are installation of a brand new G40 cam sensor and a used ECU. Both the original and replacement ECUs say "8D0 906 266B", mms-411b" "12v" and Hitachi. The original also has "6801" stamped on the red tag while the replacement has "6X01". On another tag, the original says "1353" while the replacement says "4892".
 
Back
Top