Intermittent stall when accelerating from a full stop, then car doesn't start

[Avion]

Hi,

I have a 2008 A4 B8 2.0 TDI 143 HP (CAGA engine code) with 214.000 km.

TLDR version:
Two times (once in April and once last week) the car has suddenly stalled when I tried to accelerate after a full stop, and once when I pressed down the clutch to shift up. After this the car cranks, but doesn't start again until 10-15 mins. Then it starts and runs again without any problems. No DTCs are stored, no warnings, no signs before stopping, and except this, the car is running fine, without any loss of power or anything like that. Can someone give me advice, what could be the source of this failure? Fuel pump, EGR valve, or something else?

Detailed version:
In March, after a 20 km journey the glow plug light started flashing and I experienced a loss of power. It didn't run over 3000 revs, and the max speed was ~70 km/h. Parked the car for about 1 hour, but the problem didn't disappear, so I drove home with these symptoms.
The next morning the problem disappeared, and the car worked perfectly.
A month later the car suddenly stopped (actually it felt like a stall) when I was driving in a roundabout after a full stop. While still rolling, I tried to restart the engine, but couldn't. I managed to pull over and tried to find out what is the problem. Tried again to start the engine, but it just cranked, and after a few seconds of cranking, the following message appeared: "Switch off engine and check oil level". Checked it, but the oil level was OK. After 15 minutes (and a few tries), the engine started hard, like it did not get enough fuel (or something like that), but then the car was perfectly fine again. After work I drove it to my mechanic, who said it was the DPF, and did a forced regeneration. He said there were no DTCs, or any other signs of failure.
A week later the engine stopped when I pressed down the clutch to shift up to 3rd gear, but I only noticed it because the steering wheel became hard to turn. Tried to restart, it started immediately, and everything was perfect again. The day after I searched for DTCs with VCDS, and found P0016. However, it has been set a few days after the first engine stop. Back to the mechanic, he replaced the CPS, timing belt, tensioners, water pump, etc.
After that the car worked perfectly again for two months, until last week (there was a DMF and clutch replacement because it showed signs of failure, but I don't think it is related).
So last week it has stopped again, after 30 meters when I tried to accelerate after a full stop. All the symptomps were the same: the stop felt like stalling, didn't start again after that, the same oil level warning after a few seconds of cranking. 10 minutes later it started again, and works fine. I checked for DTCs, but couldn't find any.
I would like to ask if any of you have experience with this kind of failure? Hopefully I can get some tips here, so I could take it to the mechanic with some information instead of just replacing random expensive components. What could cause this failure? Fuel pump, EGR valve, or something else?
I hope I can get it fixed, because this is a dangerous problem, and I'm a bit afraid of driving the car, as I don't know when it will stop next time.

Thank you in advance!

PS: English is not my native language, please excuse any errors on my part.

[Theiceman]

i am not sure that engine was equipped in N/A cars so we may have a hard time helping you as most people here are from US/ Canada

[Avion]

i am not sure that engine was equipped in N/A cars so we may have a hard time helping you as most people here are from US/ Canada

Oh, I'm sorry, I didn't realize that :(
Thank you for notifying me!

[Theiceman]

there may be other cars that were equipped with the 2.0 tdi , like VW maybe ?

[cjt671]

...

[Avion]

there may be other cars that were equipped with the 2.0 tdi , like VW maybe ?

I did a bit of googling, and yes, you're right, a few Passats and Seats were equipped with this engine. I will try to find information on VW forums too, thanks.

[Avion]

With no error codes it sounds like a bad crank position sensor. When they start to fail they can cause intermittent stalling and usually no start conditions when the car is hot. Once the car cools down the car starts normally. I have seen it on three of my Audis..

Thanks for your reply!
Last time the car stalled after 10 secs of driving, so the engine was not hot yet, but it was a hot day and the car parked under the Sun. Does it matter?
And the first time the engine temperature was something like 70°C.
But it seems like an inexpensive part, so it does worth a try. Do you know if the replacement needs some special actions to be done, or I can do it myself?

[misiak]

A friend of mine just replaced his crank position sensor on his Audi B7 2.0T, I think the sensor was $35 or $40 and it took us about 15 mins to replace.

[cjt671]

Thanks for your reply!
Last time the car stalled after 10 secs of driving, so the engine was not hot yet, but it was a hot day and the car parked under the Sun. Does it matter?
And the first time the engine temperature was something like 70°C.
But it seems like an inexpensive part, so it does worth a try. Do you know if the replacement needs some special actions to be done, or I can do it myself?

On one car the issue was intermittent stalling, regardless of temperature and on another the symptom was failure to start after the engine was warm. The car would start up with no problem once the engine cooled down.. this is because the crank sensor works using magnetism and heat breaks downs magnetic fields so an old or failing sensor is more prone to that problem.

It is normally a straight forward repair that doesn’t require any special action afterwards and in the Vw/Audi world the sensor is usually held in by one Allen/hex head bolt but it may take some effort/twisting and gentle prying to remove if there is any corrosion built up. The sensor isn’t always in a convenient location but it’s usually easy enough to get to.


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[Avion]

Thank you for the answers guys!
I will try to locate and change the sensor, and if I have any updates, I will write here.

Thank you again!

[cjt671]

Thank you for the answers guys!
I will try to locate and change the sensor, and if I have any updates, I will write here.

Thank you again!

Sometimes there is a spacer on the sensor. Be sure to check for it on the sensor or the engine as it usually doesn’t come with the new sensor..


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