P0299-002 Low Boost

5.0 V10 50v biturbo - 571 bhp
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BobBobson
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Posts: 15
Joined: Mon Mar 29, 2021 8:11 pm

P0299-002 Low Boost

Post by BobBobson » Wed Jul 14, 2021 5:46 pm

Hi all,

Coming off a roundabout earlier I noticed the car was down on power, albeit still running smoothly. Looking on VCDS I have the following:

Code: Select all

-------------------------------------------------------------------------------
Address 01: Engine (BUH)       Labels:. 07L-910-552-BUH1.clb
   Part No SW: 4F1 910 552 D    HW: 4F1 907 552 A
   Component: 5.0L V10/4V TFSI   ª0080  
   Revision: F1H05---    Serial number:               
   Coding: 010D0003190F01B0
   Shop #: WSC 00000 000 02400
   VCID: 2517F433E9E5EE73DC5-8070

2 Faults Found:
000665 - Boost Pressure Regulation 
               P0299 - 002 - Control Range Not Reached
             Freeze Frame:
                    Fault Status: 01100010
                    Fault Priority: 2
                    Fault Frequency: 2
                    Reset counter: 255
                    Mileage: 147958 km
                    Time Indication: 0
                    Date: 2021.07.14
                    Time: 12:19:11

             Freeze Frame:
                    RPM: 4444 /min
                    Load: 76.4 %
                    Speed: 72.0 km/h
                    Temperature: 76.0°C
                    Temperature: 59.0°C
                    Absolute Pres.: 1010.0 mbar
                    Voltage: 13.335 V

006435 - Please Check DTC Memory of ECU Number 2 
               P1923 - 008 - 
             Freeze Frame:
                    Fault Status: 01101000
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 255
                    Mileage: 148012 km
                    Time Indication: 0
                    Date: 2021.07.14
                    Time: 16:43:36

             Freeze Frame:
                    RPM: 0 /min
                    Load: 0.0 %
                    Speed: 0.0 km/h
                    Temperature: 58.0°C
                    Temperature: 60.0°C
                    Absolute Pres.: 1010.0 mbar
                    Voltage: 11.938 V

Readiness: 0000 1000

-------------------------------------------------------------------------------
Address 11: Engine II        Labels:. 07L-910-552-BUH2.clb
   Part No SW: 4F1 910 552 D    HW: 4F1 907 552 A
   Component: 5.0L V10/4V TFSI   ª0080  
   Revision: F1H05---    Serial number:               
   Coding: 010D0003190F01B0
   Shop #: WSC 00000 000 02400
   VCID: 2517F433E9E5EE73DC5-8070

1 Fault Found:
000665 - Boost Pressure Regulation 
               P0299 - 002 - Control Range Not Reached
             Freeze Frame:
                    Fault Status: 01100010
                    Fault Priority: 2
                    Fault Frequency: 2
                    Reset counter: 255
                    Mileage: 147958 km
                    Time Indication: 0
                    Date: 2021.07.14
                    Time: 12:19:11

             Freeze Frame:
                    RPM: 4443 /min
                    Load: 76.8 %
                    Speed: 72.0 km/h
                    Temperature: 76.0°C
                    Temperature: 59.0°C
                    Absolute Pres.: 1010.0 mbar
                    Voltage: 13.589 V
Questions:
  • Is the '-002' on the P0299 significant? Does it signify which bank for example?
  • Do I have seperate low boost errors on both ECUs or does the error in (presumably) ECU II copy across to ECU I?
  • Related to the above, is there any physical link (i,e, a plenum) between the left and right turbos? If the two banks are entirely separate then a simultaneous loss of boost in both could only be something like the diverter valves? If there is a common intake plenum then it could be either side. Alternatively it might only be one bank but two messages.
I'm going to log some values while driving to see if I can find anything but I don't have a good feel for the mechanics of the intake and turbos yet. I know there's a MAP sensor for either side but there also looks to be one on the intake manifold... :shock:

Thanks!

ruedisrs6
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Posts: 39
Joined: Fri Mar 29, 2019 12:16 pm
Location: Hockenheim, Germany

Re: P0299-002 Low Boost

Post by ruedisrs6 » Fri Jul 16, 2021 10:07 am

Some answers to your questions:
1. You have to specifically check the errors on ECU #2 by selecting module 11. The errors of the ECU #2 are not displayed in the error list of ECU #1, but rather the presence of error(s) in ECU #2 is listed as an error in ECU #1 (like the 2nd error in your case).
2. The turbos are entirely separated from each other. There is a separate diverter valve for each turbo which is mounted at the bottom of the air filter housing. You may want to check for boost leaks there.
3. There are plenty of sources for boost pressure regulation errors starting from vaccuum/boost leaks, intercooler leaks, wastegate control malfunction including the electric valve or even pressure sensors.
Hope this helps somehow.
Best.

BobBobson
Neutral
Posts: 15
Joined: Mon Mar 29, 2021 8:11 pm

Re: P0299-002 Low Boost

Post by BobBobson » Fri Jul 16, 2021 9:46 pm

Thanks for the help! For anyone who finds this later, the hose from the right hand intercooler had popped off at the bottom of the cast aluminium inlet duct. The car ran remarkably well with hardly any boost!

Looking at http://www.ianhenshall.com/C6_RS6_Study_Guide.pdf, ECU 1 monitors the right hand pressure sensor and ECU 2 monitors the left hand side. The turbos both feed into a common plenum in the inlet manifold, so a huge leak on one side caused low boost errors on both ECUs simultaneously. I was actually happier about having two errors rather than one as I couldn't imagine both turbos failing simultaneously even with my luck.

Other possible causes of low boost errors are listed on Ross-tech's website:
http://wiki.ross-tech.com/wiki/index.ph ... 299/000665

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