P0299 - Audi A6 2.0 Ultra limp mode

[Amigo]

I took my religiously-serviced car on a trip to Europe and I was on a toll road in France when the engine light came up and then the car entered limp mode. I managed to get the car to a service station, where I hooked up VCDS and saw two P0299 faults, 19225 and 25710. I cleared the faults and then took the bite and drove another 250km to destination without a hitch, admittedly driving rather sedately at first, but then pushing it to 100mph in Germany with no issues.

I managed to find a garage service in Germany who will see me this morning for an assessment, let's see what they say. I had a look around the engine and all I could see was some soot, I think between the turbo and EGR.

Is there anything I need to suggest the garage to investigate? Do I stand a chance of finishing the rest of my 2,500 miles trip around Europe, or cancel it?

[Sergiu_zee]

Hey
Try map sensor. Mine did the same and changed the map sensor and it was fine. If you turn the engine off and on it usualy goes away for a while and it reappears when you crawl in trafic.keep us posted.

Sent from my SM-S908B using Tapatalk

[Crasher]

The A6 Ultra is very prone to problems with the reductant injection system injecting too much AdBlue into the DPF and causing the entire system to become clogged with cement like urea crystals that are extremely difficult to remove, have you noticed an increase in AdBlue consumption?

[Amigo]

I cleared the DPF last summer with the DPF Clean Team in Hinckley and they said that the DPF was very clean of AdBlue, they did not have to bake it, as they do with many similar DPFs, they said. I did not notice an increase in AdBlue consumption, and I filled it up a couple of days ago before setting off.

I got near a WiFi with my laptop, and here's the Engine Management ECU log:

-------------------------------------------------------------------------------Address 01: Engine (J623-DDDA)       Labels:. 04L-907-309-V1.clb
   Part No SW: 04L 906 021 HA    HW: 04L 907 309 AA
   Component: R4 2.0l TDI   H20 3830  
   Revision: 8DH20---    CVN: 97CCEE40C19C7771D45710C1
   Coding: 12254012246401080000
   Shop #: WSC 02391 785 00200
   ASAM Dataset: EV_ECM20TDI01104L906021HA 004003
   ROD: EV_ECM20TDI011_AU57.rod
   VCID: 6B9615CC82A611CB0E-803E
   VINID: 9D196AAAA117A187801491490CBD2BEB79


2 Faults Found:
19225 - Boost Pressure Regulation 
          P0299 00 [101] - Control Range Not Reached
          Not Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 2
                    Fault Frequency: 1
                    Mileage: 250524 km
                    Date: 2023.08.11
                    Time: 14:13:44


                    Engine RPM: 2266.00 /min
                    Normed load value: 93.7 %
                    Vehicle speed: 130 km/h
                    Coolant temperature: 92 °C
                    Intake air temperature: 141 °C
                    Ambient air pressure: 980 mbar
                    Voltage terminal 30: 12.520 V
                    Unlearning counter according OBD: 40
                    Charge air pressure: specified value: 2743 hPa
                    Charge air cooler inlet: pressure sensor 1 bank 1: raw value: 2328.0 hPa
                    Mass airflow sensor 1 bank 1 airflow: raw value: 1021.2 mg/stroke
                    Exhaust recirc.valve 1 bank 1: posit.feedback - Actual value: 0.06 %
                    Throttl.valve adapt. 1 bank 1: posit feedback - Actual value: 0.06 %
                    Turbine actuator 1 bank 1: posit.feedback - Actual value: 76.79 %
                    Mean injection quantity: 60.03 mg/stroke


25710 - Boost Pressure Regulation 
          P0299 00 [101] - Control Range Not Reached
          Not Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 2
                    Fault Frequency: 1
                    Mileage: 250524 km
                    Date: 2023.08.11
                    Time: 14:13:44


                    Engine RPM: 2255.50 /min
                    Normed load value: 93.7 %
                    Vehicle speed: 130 km/h
                    Coolant temperature: 92 °C
                    Intake air temperature: 141 °C
                    Ambient air pressure: 980 mbar
                    Voltage terminal 30: 12.520 V
                    Unlearning counter according OBD: 40
                    Charge air pressure: specified value: 2744 hPa
                    Charge air cooler inlet: pressure sensor 1 bank 1: raw value: 2328.0 hPa
                    Mass airflow sensor 1 bank 1 airflow: raw value: 1029.8 mg/stroke
                    Exhaust recirc.valve 1 bank 1: posit.feedback - Actual value: 0.10 %
                    Throttl.valve adapt. 1 bank 1: posit feedback - Actual value: 0.06 %
                    Turbine actuator 1 bank 1: posit.feedback - Actual value: 76.78 %
                    Mean injection quantity: 60.66 mg/stroke


Readiness: 0 0 0 0 0 


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

Engine code is DDDA, with Shell V-Power Diesel exclusively since new. In June it had a full service, with engine oil change, gearbox oil change, and engine and gearbox sump replacements.

All I could find from a visual inspection was soot, as per the enclosed. The service here in Germany turned out not to deal with engine issues, so I am on my own for now. I did take the car today on a run on an Autobahn without speed restrictions and it pulled as expected, with up to 4,500rpm and up to 100mph, without a glitch or hesitation. I will be continuing my trip tomorrow for another 800 miles in one go, and at the destination I may have access to an excellent garage that my brother uses.

I was wondering if the problem appeared because I had been driving for 4 hours at 80mph on the French toll roads, in heat over 30 degrees, without much load/speed variation. At 80mph the car drives in the 7th gear at about 1,800rpm, so in order to increase my chances of reaching my destination in 800 miles tomorrow, should I drive sedately, or should I give it a full whack, even go into manual mode to increase the RPM, especially on the Southern Germany Autobahns where I'll be driving for about 4h tomorrow morning

[Crasher]

Have a look at the soot loading values

[Amigo]

Update after 850 miles in one day.
@Crasher Soot level 26mg/17mg estimated/measured, or the other way around, at the time of the second occurence.

The fault returned, but under a very specific circumstance, identical to the one before, but only the second time I realised the similarities. Conditions for the fault code:
- Stopped at a motorway service station after a few hours of driving at 80mph
- Short distance/time between leaving motorway and stopping
- Break of 10 mins in one case and 1h in another
- Outside temperatures of 32 degrees
- When leaving, driving a short distance to the motorway and accelerating to the traffic speed caused the fault code to appear

I may be wrong, but I suspect heat soak, how likely is it? I am thinking that because we also stopped a few other times to refuel with no hitch, but in each instance we refueled about 5 mins away from the motorway, meaning that the car left the motorway and drove slower for a mile or two, and the same after refuelling. Turbo Wastegate may be an issue? I don't know if the soot between the Turbo and the EGR is concidental or consequential. Any ideas welcome.

I think that I can keep the car going gently for another week until I reach a garage that will look into it and seems to be quite clued up. Any thoughts?

[Crasher]

26 is getting there, the way to find out if it is urea crystals is to do a service regen, watch the soot drop to circa 5g calculated and the measured goes negative (think that's the right way around) and then after cycling and a quick drive, the figure goes back to where it was.

[Amigo]

Makes sense, that's something to probably do when back in the UK.

[Amigo]

Does anyone have access to a parts database to obtain the Genuine OEM part number for the Wastegate Actuator for VIN No WAUZZZ4GXHN059593?

[Crasher]

04L 198 716 J £207.36 retail inc.