Audi A6 (2014) 2.0 tdi - Turbo under boost issue help (p0299)

[AnthT_A6]

I've got an intermittant low boost fault on the Audi A6 (p0299 issue)

While poking about, I noticed this Air pressure sensor was missing its fixing bolt. I tried to put a bolt in, but it seems to be cross threaded (hence the cable tie) 
The other odd thing, the sensor seems to only have one pipe plumbed in. One pipe looks like it goes into the dpf, the other is not connected to anything.

surely this can't be right

By any chance does anyone have an A6 and could have a quick look?

 

Edited June 3, 2022 by AnthT_A6

[Stevey Y]

10 hours ago, AnthT_A6 said:

I've got an intermittant low boost fault on the Audi A6 (p0299 issue)

While poking about, I noticed this Air pressure sensor was missing its fixing bolt. I tried to put a bolt in, but it seems to be cross threaded (hence the cable tie) 
The other odd thing, the sensor seems to only have one pipe plumbed in. One pipe looks like it goes into the dpf, the other is not connected to anything.

surely this can't be right

By any chance does anyone have an A6 and could have a quick look?

 

Hi both pipes should go to the DPF one before and one after the DPF that is why its known as a pressure differential sensor as it measures the air pressure going in and the pressure at the other end going out, thats how it knows when the DPF is blocking, check to see if either pipe is broken as that will be your problem.

Steve.

[AnthT_A6]

Thanks Steve

That’s interesting.

Before covid, the car did mostly motorway miles, now that I mostly work from home, I’m doing shorter journeys.

I have a feeling it’s actually a DPF issue and maybe the previous owner had something done to trick it.

im going to give it a long steady trip up the motorway, see if it makes a difference.

I’ll also continue to investigate and find out why it’s not connected 

I can’t see anything it would connect too

 

very strange

 

[Stevey Y]

16 minutes ago, AnthT_A6 said:

Thanks Steve

That’s interesting.

Before covid, the car did mostly motorway miles, now that I mostly work from home, I’m doing shorter journeys.

I have a feeling it’s actually a DPF issue and maybe the previous owner had something done to trick it.

im going to give it a long steady trip up the motorway, see if it makes a difference.

I’ll also continue to investigate and find out why it’s not connected 

I can’t see anything it would connect too

 

very strange

 

Hi as I said both pipes should connect one to a metal pipe before the DPF and the other to a metal pipe after the DPF, its in there somewhere, have the splash pan off and have a look from underneath.

Steve.

[Stevey Y]

29 minutes ago, Stevey Y said:

Hi as I said both pipes should connect one to a metal pipe before the DPF and the other to a metal pipe after the DPF, its in there somewhere, have the splash pan off and have a look from underneath.

Steve.

 

50 minutes ago, AnthT_A6 said:

Thanks Steve

That’s interesting.

Before covid, the car did mostly motorway miles, now that I mostly work from home, I’m doing shorter journeys.

I have a feeling it’s actually a DPF issue and maybe the previous owner had something done to trick it.

im going to give it a long steady trip up the motorway, see if it makes a difference.

I’ll also continue to investigate and find out why it’s not connected 

I can’t see anything it would connect too

 

very strange

 

Hi disregard the previous post as I have just looked at mine and its the same as yours apparently the pipe with no connection measures the atmospheric pressure against the the realtime pressure from the pipe that is connected to the DPF via a long metal pipe, I think you are probably right about the DPF issue as the variables for that code are massive anything from boost control valve, clogged turbo vanes, boost diverter valve, they all lead to one thing a build up of crud, the cheapest option is give it a bottle of Wynns EGR cleaner and give it a nice long run down the motorway if that sorts it the crud in the emissions system is your problem, from a quick research even Audi have problems diagnosing this one. All these cost cutting solutions they come up with just create more problems than they solve for the end user.

Steve.

[AnthT_A6]

brilliant! Thanks Steve 

that one thing I can tick off the list

im really surprised that Audi left a pipe connected (the little 90 degree pipe)

[AnthT_A6]

The plot thickens.
The sensor appears to be the wrong one, it’s 059906051B and it should A.

We have owned the car since 2016 and never had any problems.

It’s odd that we have the wrong sensor, almost feels like someone deliberately swapped it.

[Stevey Y]

On 6/6/2022 at 9:12 PM, AnthT_A6 said:

The plot thickens.
The sensor appears to be the wrong one, it’s 059906051B and it should A.

We have owned the car since 2016 and never had any problems.

It’s odd that we have the wrong sensor, almost feels like someone deliberately swapped it.

Hi don't take any notice of the letters at the end of the part number as these are denomination for the year of supply, there are many who believe this letter to be critical, its not and a prime example of this is the glow plug on cylinder three it has a pressure/knock sensor built in, mine went sideways before the bank holiday and kept throwing an EML with a code for an implausible signal, it was on its way out, the part number for our cars is 03L 905061G, the plug they sent me was 03L 905 061K thats the supersession number, it fits, it works wonderfully and no more EML, I rest my case, BTW the same plug is fitted to the A5 A6 and several Volkswagen models.

Steve,

[AnthT_A6]

Thanks again Steve

yes, I’ve since found that out. I work for Jaguar Land Rover, our version control in part numbers are different, I didn’t think outside my box 😄

The car is in getting a new sensor, hopefully this enables a DPF regen and fixes the issue 

[Stevey Y]

22 hours ago, AnthT_A6 said:

Thanks again Steve

yes, I’ve since found that out. I work for Jaguar Land Rover, our version control in part numbers are different, I didn’t think outside my box 😄

The car is in getting a new sensor, hopefully this enables a DPF regen and fixes the issue 

Hi when you fit the new sensor don't forget the adaptation for the new unit and before you give it a regeneration check the ash/soot levels.

Steve.

[Haider]

Hi mate did you manage to find out and fix this problem?

[Haider]

Hi

Edited August 14, 2022 by Haider

[AnthT_A6]

Sorry, yes, I should have posted about it.

turned out it was a sensor that had failed (not the one I thought it was) 

the garage said it was a boost control sensor, but that is the only info I have