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Audi A6 C7 No Power & Wont Drive


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Hi all,

 

I am new here so sorry if I don't post things in the correct format or to how you are all used to. Basically to put it as it is, my car appears to be f*cked. Now theres several things surrounding the symptoms to which im hoping you can all help me diagnose. Let me start from the beginning.

-Firstly, I had an issue with the DPF saying the system had malfunctioned etc. To combat this and to future proof any other issues, I bought VCDS and forced a regeneration which seemed to solve this issue for a short period of time.

 

-Then the issue came back combined with a Oxygen sensor fault. So I replaced the oxygen sensor, cleared errors and forced another DPF regeneration. This resolved all issues.... for the time being.....

 

-The DPF issue came back again and again almost on a monthly cycle. Now my car is used for a lot of short journeys due to my wife being a carer, so I assumed its because of this the soot isn't getting a chance to burn off...

-Then the DPF issue came back but this time with the glow plug light flashing. After reading up it was apparent this is a know cause of the DPF again or other issues (not necessarily the glow plugs even though it did find an error on cylinder 2 glow plug). I ran the DPF regeneration again and cleared faults. All seemed to be fine for a few weeks, Then boom, the same issue... But this time car goes into limp mode. Repeated the same steps then all was fine.

-A few days ago, DPF error comes up again with the glow plug light, but after reading the codes this time it throws up the cylinder 2 glow plug and the G40 speed sensor. So today I had the glow plugs replaced and reset the codes but after this the glow plug light was still on and the g40 speed sensor code still remained and the car remained in limp mode. I drove the car home (approx half a mile) and proceeded to run the DPF regen on my drive but it wouldn't complete so I had to abort the procedure. When reading the soot levels it was reading as 33.60g soot levels.

 

I Decided to test it round the block and it lost all power. I couldn't even reverse onto my drive, it actually stalled, so I had to push it back on.

Im thinking it could either be 1 of 2 things or a combination of both.

1. DPF is fully blocked, 2. g40 sensor is blocked, 3 combination of both. My questions are;

 

Regarding sensor: where is the g40 sensor located on my audi? what is the actual part number for this sensor?

Regarding DPF: where is this located (under bonnet or under car), do you think it sounds blocked? Would you get it removed and bypassed?


Sorry for such a long post, I just thought its best I fit as much in as I can think of. If you need any other information please do no hesitate to ask. 

 

 

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Hi I think the G40 or crankshaft position sensor is probably located behind the cam belt housing but if you can send me your VIN NO I can check it on my ETKA system which will with a bit of luck throw up A. the exact location, B a part number, the reason the DPF is blocking is because this sensor is malfunctioning and the ECU won't sanction any regeneration because it thinks doing that may damage the engine, furthermore I would not recommend a DPF delete especially if the car runs adblue as your likely to need VCDS to keep putting out the Christmas tree lights on the dash, then there is always the issue of increased emissions.

the DPF is under the cat on the left hand side of the engine and from what I have seen you have to remove most of the front of the car, you might be better served sorting the sensor do a regeneration and see how you go, other than that if you are still not happy try Terraclean.

A man with information and codes, priceless......

Regards Steve.

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Thank you, I will post my vin in the morning to see if you can locate the exact position and take it from there 🙂 . Also I do have VCDS, which tbf has been a life saver

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Hi Ryan I have an airport take out and pick up to do but I will get to it as soon as I get back and should have your answers for you late afternoon if thats O.K. in my line of work you have to grab what you can when you can, BTW the sensor we are looking for cannot block up as its a Hall sensor, [solid state] so like an ABS sensor it relies on a circular metal ring with teeth or a magnetic ring to function.

Cheers mate.

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1 hour ago, Stevey Y said:

Hi Ryan I have an airport take out and pick up to do but I will get to it as soon as I get back and should have your answers for you late afternoon if thats O.K. in my line of work you have to grab what you can when you can, BTW the sensor we are looking for cannot block up as its a Hall sensor, [solid state] so like an ABS sensor it relies on a circular metal ring with teeth or a magnetic ring to function.

Cheers mate.

Not a problem I totally understand about grabbing the work whilst you can. With it still being a sensor, could this still be the reason for the loss of power/cutting out?

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Hi Ryan,

Boredom is a terrible thing, I have been sitting in the car playing with the laptop whilst waiting, right there appears to be two choices depending on which engine you have [usual bullocks] but the good news is they are not big bucks to buy, the downside is the diagram showing the sensors is showing them in a large white area with no indication of where they go, very frustrating, but I was talking to my mate who installed my VCDS and driver and he pointed out that the part no you want for the sensor will be in the description of the fault, that narrows it down and why did I not remember that, must be going senile, if you can throw in an engine code I can go down to one of my customers garage tomorrow and hijack his Autodata repair programme and find out where its located.

Have a look at the fault code again and see if either of these part numbers throw up a flag, 03L 957 147A.or     04L 907 601. With regard to the sensor causing the loss of power and it cutting out, most definitely that is the cause as the ECU cant get its head round mixed signals so if the fault gets that bad it simply shuts the whole thing down or goes into limp mode, I had it with a Ford cab I had coming home from stansted one night, going through the lanes the !Removed! thing kept cutting out not good at half past stupid in the morning, so I nursed it down to the only garage for miles got the reader out and scanned it, it showed crank position sensor intermittent fault so after a bit of head scratching a bored AA man that patrols that area walked over and asked whats the matter when I showed him the scanner he went and got his big search light torch and we had a look. 

the fault soon became apparent as when idling there was a steady drip of coolant coming from the water pump and down on to the crank sensor so I bought an overpriced Bars Leak from the garage put that in the coolant tank, WD40d the sensor to death and made a run for home, if any sensor starts to break down internally the only answer is replacement.

Regards Steve.

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I have ran another test and heres what VCDS has throws up. The car took ages to start and when it did it ran rough. try revving the car and it had no power, it wouldn't even get above 1000rpm

------

1 Fault found:

4096 - Bank 1: CMP Sensor (G40)/Engine Speed Sensor (G28)
P0016 00 [167] - Incorrect Correlation
MIL ON - Not Confirmed - Tested Since Memory Clear

Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 204852 km
Date: 2021 .02 .14
Time: 13:26:35

Engine speed: 877.50/min
Normal load value: 50.6%
Vehicle speed: 0km/h
Coolant temperature: 12c
Intake air temperature 3c
Ambient air pressure: 1000 mbar
Voltage terminal 30: 13.740 V
Unlearning counter according ODB: 40
Engine start: start synchronization: EPM_MODE_OK
Engine start: start synchronization-Test_Program_Epm st Op Mode State t UBY

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After reading up it could be that the timing has slipped slightly 😢

That sounds like an expensive job, long job

**Possible Causes**
Timing Issue
Camshaft Adjuster

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4 hours ago, BigTownz said:

After reading up it could be that the timing has slipped slightly 😢

That sounds like an expensive job, long job

**Possible Causes**
Timing Issue
Camshaft Adjuster

Hi Ryan bear with me as these are pretty new to me but the principles remain the same, had a study up on the VVT system its the same as most manufacturers these are electromagnetic devices that use controlled oil flow to advance or !Removed! the valve timing via the camshafts, other manufacturers just the same thing but a more complex valve system like BMW the VANOS system, when these fail they cause performance issues, sluggish engine performance not a partial shutdown or other peripheral problems, vet units either work or don't and seem to have their own set of DTCs.

So if you go back to your original post changing the oxygen sensor was a good shout as thats pretty close to the recommended milage change interval anyway, the glow plugs again good housekeeping,  but subject to the latest scan information my money is still on the G40 sensor as its not talking properly to the G28 sensor, swapping readings hence the term correlation in other words the G40 is supplying G28 with no plausible information, anything to do with engine sensors will affect the engines ability to start a regeneration forced or otherwise.

We need to know what engine code you have and the BHP of your engine, mine is 190 BHP CNHA engine, they seem to build virtually the same engine but with different horsepower and engine code denominations if I can find where G40 is hiding I am sure that may well be the answer the timing cannot slip.

Regards Steve. 

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12 minutes ago, BigTownz said:

I've tried this site and it dont seem to be any good for me. Cant find the part and it dont recognise my VIN

Thats because it is dated and has a lot of non specific info.

Steve.

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Im looking at my log book and the BHP is in KW? 140KW is the power which after googling equates to 187bhp (190),engine number is CHNA045295, also under "variant" it states ACNHAF1 if this helps?

Thank you for your time, its much appreciated.

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33 minutes ago, BigTownz said:

Im looking at my log book and the BHP is in KW? 140KW is the power which after googling equates to 187bhp (190),engine number is CHNA045295, also under "variant" it states ACNHAF1 if this helps?

Thank you for your time, its much appreciated.

Hi Ryan I am pretty sure the engine is the same as my 2016 Avant which makes things a little easier as I can use my engine as a realtime source for visual sensor hunting, all good information. the internet is a wonderful tool if you can sift through the information and find what exactly is relevant to your problem, if you read  it all and believe it all like a mate of mine his death has been imminent for the last fifteen years, will get back to you tomorrow evening.

Steve.

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53 minutes ago, gently said:

Thats the site I found which made me think my timing had slipped. I guess its a process of elimimation and to start with the sensor should be changed first as this is the next logical step.

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14 hours ago, Stevey Y said:

Hi Ryan I am pretty sure the engine is the same as my 2016 Avant which makes things a little easier as I can use my engine as a realtime source for visual sensor hunting, all good information. the internet is a wonderful tool if you can sift through the information and find what exactly is relevant to your problem, if you read  it all and believe it all like a mate of mine his death has been imminent for the last fifteen years, will get back to you tomorrow evening.

Steve.

I have rang Audi today regarding the sensor and they have stated the G40 sensor brings up 4 different part numbers but he didn't want to give them to me 😣. Cost for a sensor starts at £70.27+vat and takes approx three days to arrive as they don't keep them in stock. Also I would need to remove the old sensor and take it up to them so they can match it 😠😠😠. Believe it or not this was a main dealership and they seemed like they didn't even know what they were talking about. I also asked where the sensors are located and his reply was, he don't know, normally close to the crank casing

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So, after trawling the net I think I have found the sensor I requir (G40) for a cheaper price than Audi quoted, I just need to locate the old one to compare the OEM number and visual elements 


image.thumb.png.9090907100f0caff1081ce2ac8d28858.png
 

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Hi Ryan.

Hold the press I used my break today and go and see a couple of people and ended getting involved in a sensor tour of my engine, the Autodata did not pan out as it did not cover your engine and any late engine come to that, apparently you have to pay a massive subscription now and go on line, this has stopped a lot of garages using cloned discs off of the net.

The second guy was pure gold he showed me where the G40 and the G28 sensor are located I even found out where the VVT unit was, he does a lot of Audis and VWs and started to show me data logs from some of his repairs at least four of them were nigh on the same as yours, so I showed him the picture of your scan he then proclaimed that I know what that might be and gave me a repair triage, from the top, have you had the cam belt changed recently as the guy has found through experience that if left to the recommended change interval often as not they stretch, they rarely break but will stretch quite a bit, case in point a beetle he had there that had come in with the same symptoms is all he had done was change the timing belt kit, cleared the codes and it ran like a Swiss watch he then showed me a new belt against the old belt which you could definitely see the difference.

So  he advised the following, have the valve timing checked not difficult as I watched him do my cam belt a couple of months ago and if you can find a decent independent garage they as he has will have the right locking pin kit.

If the belt has been changed recently then the most likely suspect is the G40 camshaft sensor which is housed inside the cam belt cover the crank sensor is underneath on the right hand side rear of the engine when viewed from the front of the car. what you have there in the picture is a crank sensor as advertised but the other sensor for the cams has a wire and a plug unit attached, I will go back to my system and using the new info you gave me will see if I can get one definitive part number.

As for the dealers don't worry about them they are all brain dead as I found out last summer when I bought two new headlight bulbs, they were adamant that they were D5S bulbs so consequently when I tried to change them it turns out they were D3S original bulbs so the new ones won't fit, another seventeen mile round trip to take them back and even when I showed them the pictures of my original bulbs they still said I was wrong and did not want to replace them because I had opened one of the boxes, I asked for a refund they refused that until I stood in the service counter and phoned Barclays to ask them to stop or recover my payment, they gave me a refund on the spot.

Regards Steve. 

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Thank you for this information. Since owning the car for the past 2 years I haven't had the cam belt changed and when I bought it, it was already on 110,000. I have just checked for the service manual and it doesn't seem to be in the pack, maybe I have moved it to another folder or even worst lost it 😞. I will ring Audi in the morning and see if they have the history of the vehicle.

In regards to the cambelt cover I think mine is at the front of the engine (Closest to the bonnet) not rear.

Looks like I will have to bite the bullet and have it recovered to a local garage. Just to pick your brains, do you think my engine could be damaged if the belt has stretched? I feel it maybe the belt over stretching over the sensor.

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Hi, Ryan,

110,000 is the recommended  change interval and I wouldn't mind betting thats why the previous owner sold it, you won't have a service booklet because they did away with them years ago, is all you get now is a piece of paper sent to you with the service history as far as they have serviced it, this won't include any independent or quick fit service history.

With regard to any engine damage I seriously doubt there will be any as it still tries to run but subject to my conversation with William today if the belt has not been changed that could well be the source of your problem, you would be best served filling in whatever garage you use on what you think might be the problem as this always stops any ideas of padding out the bill if they think you know in depth what you are talking about, show them the scan results that will impress them, the best part is my engine is the same as yours and I will log what I have learned from this for any future problems I may have.

Wish you the best of luck with this and please can you post the resolution on the forum as it gives good usable information to other forum users, and its been a pleasure talking to you.

Steve.🤓

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Morning Steve,

I have managed to find a video which shows the cam belt change and the sensor location for our model. It looks like on our model the sensor is integrated with one of the tensioners/pullies and as you correctly described it has a wire coming off it too. The only problem for me is the video isn't in English 😆. I have coded the video link, not sure if this is required on this site? I have already spoken to a garage (8am lol) and I'm currently awaiting a call back. I will ask them to take pictures of the belt next to the replacement etc and post the results.
 

https://www.youtube.com/watch?v=49PGX_URn7A

 

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