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Discussion Starter #1
Hello to all

I am trying to diagnose the likely candidate for the root cause of an overboost fault code that I'm picking up with VCDS.

The car has had some throttle / running issues for the last month or two, which has resulted in a permanent limp mode, dodgy throttling (affected pullaway from standstill really badly) and the general inability to actually drive the car (it broke down on a short, steep hill, where it ran out of puff and couldn't even make it up in first gear).

My friend and I removed and cleaned the EGR valve & Throttle body, but this made no difference - largely making the problem worse and the car more undriveable. I bit the bullet and bought brand VDO EGR and Throttle Body units - fitted them, and we initially thought that the car had been cured as on start-up and initial test-run, she was driving normally again (the old EGR valve was definitely broken, with a butterfly valve that was partially open when it was removed, and the valve couldn't even be turned with a screwdriver and some force!).

Anyway, during the test-run (all fault codes were cleared before she was driven), it became clear that all was not as it should be, and giving her some gentle beans and about 3,000 RPM in 2nd gear, she went straight back into limp mode again. This limp mode was less catastrophic than it was previously, as she can be driven relatively normally, but limited to about 40-50mph in 4th/5th. VCDS reports:

000564 - Boost Pressure Regulation
P0234 - 000 - Limit Exceeded (Overboost Condition)
Freeze Frame:
Fault Status: 01110000
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 211838 km
Time Indication: 0
Date: 2018.01.21
Time: 11:47:39


Freeze Frame:
RPM: 2709 /min
Speed: 62.0 km/h
Load: 58.4 %
Voltage: 13.83 V
Bin. Bits: 00101000
Absolute Pres.: 2121.6 mbar
Absolute Pres.: 2590.8 mbar

I've been through the Ross-Tech and YouTube videos to see how I can log control block data, and I think I've managed to do this - hopefully, this forum will allow me to upload the Excel .csv file that it's stored in, however, you can see a bit of a picture from the VCDS fault where it highlights the difference between the specified pressure -v- the actual pressure recorded. The .csv file shows that upto about 1,200 RPM actual is less than specified. Then upto about 2,700-2,800 revs, it's broadly inline between specified -v- actual, then from about 2,900 onwards it starts to overboost by a greater and greater margin and kicks the car into limp mode.

The car can be reset live and in realtime by VCDS during the drive, and the car immediately returns to "normal" once the code is cleared.

I'm an amateur owner/driver, that's trying to fix and diagnose myself if possible. I've watched the VNT overhaul video on this forum's YouTube channel, and my gut instinct is to suspect that the control ring/nozzles are a bit gunked up and sticky, which is leading (I think!) to a stiff and sticking wastegate actuator arm that can't work properly as a result. I've pulled off the vac hose from the top of the actuator chamber, and its sucking air well. All of the main turbo hoses and pipes all inflate (I believe) as they should when you spin up the engine and engage the turbo).

Is there anything else I can do, any other tests I can run within VCDS, or anything else I can do tinkering in the engine, to help me pinpoint what the actual cause is? Looking at the Ross-Tech Wiki - it could be the boost pressure sensor, boost pressure valve blah, blah, blah, but I'm trying to avoid the "buy a new part, fit it and see if it cures it" sort of approach!! It starts getting a bit pricey with turbo parts!

Any help, or steers, or suggestions for anything else I can possibly do to pinpoint the issue would be VERY much appreciated!
 

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Discussion Starter #2
I found that I couldn't upload the VCDS .csv file, so I am going to try an ugly copy and paste job of the data:

Wednesday 24 January 2018 22:59:11:30461-VCID:75E15DB81CB7CBE9CA-8020 VCDS Version: Release 17.1.3 (x64) Data version: 20170320 DS267.7
03G 906 016 MH R4 2.0L EDC G000SG 0948

Group A: '003 Group B: '011
Engine Speed Exhaust Gas Exhaust Gas Exhaust Gas Engine Speed Boost Pressure Boost Pressure Charge Pressure
TIME (G28) Recirculat. (spec.) Recirculat. (actual) Recirc. Duty Cycle TIME (G28) (specified) (actual) Control Duty Cycle
Marker STAMP /min mg/str mg/str % STAMP /min mbar mbar %
0.13 882 295 490 99.6 0.29 882 1040.4 1009.8 78.1
0.44 882 295 500 99.6 0.63 882 1040.4 1009.8 78.1
0.79 882 295 490 99.6 0.94 882 1040.4 1009.8 78.1
1.1 882 295 500 99.6 1.27 882 1040.4 1009.8 78.1
1.43 882 295 500 99.6 1.58 882 1040.4 1009.8 78.1
1.76 882 295 495 99.6 1.91 882 1040.4 1009.8 78.1
2.07 882 295 495 99.6 2.23 882 1040.4 1009.8 78.1
2.38 882 295 500 99.6 2.57 882 1040.4 1009.8 78.1
2.73 882 295 490 99.6 2.88 882 1040.4 1009.8 78.1
3.04 882 295 500 99.6 3.21 882 1040.4 1009.8 78.1
3.37 882 295 495 99.6 3.52 882 1040.4 1009.8 78.1
3.68 882 295 490 99.6 3.85 882 1040.4 1009.8 78.1
4.01 882 295 490 99.6 4.16 882 1040.4 1009.8 78.1
4.32 882 295 500 99.6 4.5 882 1040.4 1009.8 78.1
4.66 882 295 485 99.6 4.82 882 1040.4 1009.8 78.1
4.98 882 295 495 99.6 5.15 903 1081.2 1009.8 78.9
5.31 1113 345 450 99.6 5.46 1113 1050.6 1009.8 70.2
5.62 1008 295 525 99.2 5.8 966 1050.6 1030.2 76.9
5.96 1134 330 470 99.6 6.12 1155 1060.8 1030.2 67.9
6.27 1155 295 525 96.1 6.44 1155 1071 1040.4 67.1
6.59 1218 315 525 95.3 6.76 1281 1101.6 1050.6 60.4
6.91 1365 295 525 91.8 7.09 1365 1060.8 1071 60.4
7.24 1365 295 540 87.5 7.4 1386 1050.6 1091.4 60.4
7.56 1365 295 515 82.8 7.72 1407 1050.6 1101.6 60.4
7.89 1428 295 445 77.7 8.04 1428 1050.6 1101.6 60.4
8.2 1449 295 405 72.3 8.37 1470 1050.6 1091.4 60.4
8.53 1491 295 360 67.6 8.68 1533 1050.6 1081.2 60.4
8.84 1554 295 345 64.5 9 1554 1050.6 1071 60.4
9.17 1575 295 320 62.9 9.32 1575 1050.6 1060.8 60.4
9.48 1575 295 315 61.3 9.65 1596 1050.6 1050.6 60.4
9.8 1596 295 300 60.5 9.95 1596 1050.6 1050.6 60.4
10.11 1596 295 310 59 10.3 1575 1050.6 1040.4 60.4
10.46 1575 295 300 58.2 10.62 1596 1060.8 1040.4 60.4
10.77 1596 295 300 57.8 10.95 1617 1060.8 1040.4 60.4
11.11 1596 295 290 57.8 11.28 1596 1050.6 1040.4 60.4
11.44 1617 295 285 57.8 11.59 1617 1060.8 1040.4 60.4
11.75 1596 295 300 55.5 11.91 1617 1060.8 1040.4 60.4
12.09 1596 295 295 56.3 12.24 1596 1050.6 1040.4 60.4
12.4 1617 295 290 57 12.56 1617 1050.6 1040.4 60.4
12.72 1659 295 285 58.2 12.88 1680 1071 1040.4 60.4
13.04 1659 295 290 58.2 13.19 1701 1081.2 1040.4 60.4
13.37 1743 295 295 58.6 13.53 1722 1081.2 1040.4 60.4
13.68 1743 295 285 58.6 13.84 1764 1101.6 1050.6 60.4
14.01 1764 295 300 58.2 14.19 1764 1111.8 1050.6 60.4
14.33 1764 295 305 57 14.5 1785 1101.6 1050.6 60.4
14.66 1806 300 305 58.2 14.83 1785 1101.6 1050.6 60.4
14.97 1806 305 300 59 15.13 1806 1111.8 1060.8 60.4
15.3 1848 305 295 60.5 15.46 1890 1132.2 1060.8 60.4
15.61 1848 305 305 58.6 15.77 1890 1132.2 1071 60.4
15.95 1911 305 290 61.3 16.11 1890 1122 1071 60.4
16.27 1932 310 305 60.5 16.46 1953 1132.2 1071 60.4
16.61 1932 300 305 59.4 16.77 1974 1132.2 1081.2 60.4
16.93 1953 300 310 59 17.1 1953 1122 1081.2 60.4
17.26 1974 305 305 60.2 17.42 1953 1122 1081.2 60.4
17.57 1974 305 310 60.2 17.74 1995 1132.2 1091.4 60.4
17.9 1974 305 315 59.8 18.05 1995 1142.4 1091.4 60.4
18.21 1995 305 300 60.5 18.38 1974 1142.4 1091.4 60.4
18.54 2016 310 305 60.5 18.69 2016 1132.2 1091.4 60.4
18.85 2016 305 320 58.6 19.02 2037 1152.6 1101.6 60.4
19.18 2037 315 310 60.2 19.34 2016 1152.6 1101.6 60.4
19.49 2058 315 310 60.9 19.66 2058 1162.8 1101.6 60.4
19.82 2058 310 305 60.9 19.98 2037 1152.6 1101.6 60.4
20.13 2058 325 310 62.1 20.31 2058 1162.8 1111.8 60.4
20.48 2079 330 315 63.3 20.63 2058 1173 1111.8 60.4
20.81 2058 335 310 64.1 20.96 2100 1224 1111.8 60.4
21.12 2142 350 335 65.2 21.28 2142 1244.4 1132.2 60.4
21.47 2121 350 340 65.6 21.63 2163 1244.4 1142.4 60.4
21.79 2163 350 350 65.2 21.95 2163 1254.6 1152.6 60.4
22.12 2205 355 345 66.4 22.28 2205 1275 1162.8 60.4
22.43 2226 360 360 65.6 22.59 2247 1285.2 1173 60.4
22.76 2310 370 355 65.2 22.92 2352 1285.2 1193.4 60
23.07 2415 375 355 64.1 23.23 2499 1275 1213.8 56.8
23.4 2625 400 360 64.8 23.56 2688 1275 1254.6 51.3
23.71 2751 415 400 64.1 23.87 2793 1275 1295.4 47.7
24.04 2814 415 420 64.1 24.2 2856 1264.8 1346.4 43.8
24.35 2877 420 415 64.5 24.51 2898 1264.8 1387.2 40.6
24.69 2919 420 420 64.1 24.85 2940 1264.8 1417.8 37.5
25.01 2940 425 425 63.3 25.19 2961 1264.8 1438.2 35.1
25.35 2961 425 420 63.3 25.51 2982 1264.8 1448.4 33.1
25.67 2982 425 420 63.3 25.84 2982 1264.8 1458.6 32
26 3003 425 425 62.5 26.15 3003 1264.8 1468.8 30.4
26.3 3024 430 435 62.5 26.48 3024 1264.8 1479 29.6
26.64 3024 430 440 64.1 26.81 3045 1264.8 1489.2 28.4
26.97 3024 430 440 61.7 27.13 3024 1264.8 1499.4 27.6
27.29 3024 430 425 61.7 27.44 3045 1275 1499.4 28
27.63 3066 430 430 64.5 27.78 3066 1275 1499.4 27.6
27.94 3066 430 455 63.7 28.12 3087 1285.2 1519.8 26
28.28 3108 435 450 64.8 28.44 3150 1315.8 1540.2 25.3
28.61 3171 510 500 69.9 28.77 3192 1326 1581 21.7
28.93 3192 540 585 68.8 29.1 3192 1326 1662.6 14.2
29.25 3213 560 560 69.9 29.43 3150 1285.2 1703.4 7.1
29.59 2982 400 475 52.7 29.74 2730 1101.6 1621.8 54.1
29.89 2457 330 340 27.7 30.07 2121 1040.4 1397.4 60.4
30.22 1869 295 285 30.1 30.38 1638 1030.2 1244.4 60.4
30.53 1407 295 295 28.5 30.71 1197 1030.2 1132.2 65.1
30.86 966 295 350 19.5 31.02 924 1040.4 1081.2 78.5
31.18 903 295 305 34.4 31.35 903 1040.4 1050.6 78.5
31.5 882 295 305 34.8 31.66 882 1040.4 1030.2 78.9
31.83 882 295 290 41 32 882 1040.4 1020 78.9
32.16 882 295 290 41 32.32 861 1050.6 1009.8 78.9
32.49 882 295 285 42.2 32.64 882 1050.6 1009.8 78.9
32.8 861 295 285 44.1 32.96 882 1050.6 999.6 78.9
33.13 882 295 285 44.5 33.29 882 1050.6 999.6 78.9
33.44 882 295 280 46.1 33.6 861 1050.6 999.6 78.9
33.77 882 295 295 46.1 33.93 882 1050.6 999.6 78.9
34.08 882 295 290 47.3 34.24 882 1050.6 999.6 78.9
34.41 882 295 290 46.1 34.57 882 1050.6 999.6 78.9
34.73 882 295 285 47.3 34.92 882 1040.4 999.6 78.9
35.08 882 295 290 47.3 35.24 882 1050.6 999.6 78.9
35.39 882 295 285 49.6 35.56 882 1050.6 999.6 78.9
35.72 882 295 295 48 35.88 882 1050.6 999.6 78.9
36.04 882 295 275 51.6 36.21 882 1050.6 999.6 78.9
36.37 882 295 275 53.1 36.53 882 1050.6 999.6 78.9
36.68 882 295 295 49.6 36.85 882 1040.4 999.6 78.9
37.01 882 295 290 48.4 37.16 882 1040.4 999.6 78.9
37.32 882 295 290 48.4 37.51 882 1040.4 999.6 78.9
37.67 882 295 290 50.4 37.82 882 1040.4 999.6 78.9
37.98 882 295 300 49.2 38.15 882 1050.6 999.6 78.9
38.31 882 295 300 48 38.46 882 1040.4 999.6 78.9
38.62 882 295 290 50.4 38.79 882 1050.6 999.6 78.9
38.95 882 295 285 50.8 39.1 882 1040.4 999.6 78.9
39.26 882 295 305 48.4 39.43 882 1040.4 999.6 78.9
39.59 882 295 295 48.4 39.74 882 1040.4 999.6 78.9
39.9 882 295 290 48.8 40.08 882 1040.4 999.6 78.9
40.24 882 295 285 50 40.4 882 1040.4 999.6 78.9
40.56 882 295 280 50 40.73 882 1040.4 999.6 78.9
40.89 882 295 285 50.4 41.04 882 1050.6 999.6 78.9

It's out of alignment, but that's the best I could get it to display!
 

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First posts normally go in introductions else you could get a free fix and we never see you again!!!

Forum Rules and Guidelines

If you have a genuine VAG-COM/VCDS cable make sure its registered online VCDS Dongle Registration then you can join the Ross-Tech forum.

Make a new thread about your problem with a full AutoScan added. How to post an Auto-Scan

VAG Error Code: 16618/000564

EOBD II Error Code: P0234

Fault Location:
Boost Pressure Regulation - Limit Exceeded (Overboost Condition)

Possible Cause:
Malfunction Indicator Lamp (MIL)(K83) active.
Boost Pressure too high.
Reduced Power Output.

Hoses incorrectly connected, disconnected, blocked or leaking.
Solenoid Valve for Boost Pressure Control (N75) faulty.
Manifold Pressure/Boost Sensor (G31) faulty.
Turbocharger stuck/faulty.
Exhaust Gas Recirculation (EGR) Valve blocked.

Possible Solutions:
Check Charge Pressure Control System.
Read Measuring Value Blocks (MVB).
Perform Output Test (to check the Turbocharger).
Perform Basic Setting (to check the Charge Pressure Control).
Difference of set value boost pressure vs. altitude sensor signal > 200 - 1275 hPa.
Perform Pressure Test to locate Leaks.
Check/Replace Solenoid Valve for Boost Pressure Control (N75).
Check/Replace Manifold Pressure/Boost Sensor (G31).
Check/Replace Turbocharger.
Check and clean Exhaust Gas Recirculation (EGR) Valve.

Description:
The boost pressure sensor responds to pressure changes in the intake manifold. This pressure is created by the turbocharger and changes with accelerator pedal position and engine speed. The Engine Control Module (ECM) uses this information to assist in diagnosis of the barometric pressure (BARO) sensor and to provide engine overboost protection. The boost pressure sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The Engine Control Module (ECM) supplies 5 volts to the boost pressure sensor on the 5-volt reference 2 circuit, and provides a ground on a low reference circuit. The boost pressure sensor provides a signal to the Engine Control Module (ECM) on a signal circuit relative to the pressure changes. The Engine Control Module (ECM) monitors the boost pressure sensor signal for voltage outside of the normal range. The Engine Control Module (ECM) calculates a predicted value for the boost pressure sensor. The Engine Control Module (ECM) then compares the predicted value to the actual signal.

As taken from my new Free EOBD II Error Codes software
 

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Discussion Starter #4
First posts normally go in introductions else you could get a free fix and we never see you again!!!

Forum Rules and Guidelines
Hello Keith

Please accept my apologies for the oversight on my part. I did not know that this was the etiquette on this forum, and please accept my apologies if I've done the wrong thing here.

If you have a genuine VAG-COM/VCDS cable make sure its registered online VCDS Dongle Registration then you can join the Ross-Tech forum.
I've been trying to use the Ross-Tech forum for months, having registered the VCDS cable with the website as soon as I got it. I've done all of those steps, but am still not able to use the forums, despite their website confirming that my VCDS cable is accepted as being registered! A number of emails to the forum mods, with no response, and I've given up with them. Hence me trying to uncover the root cause of my problem here.

I wouldn't call it a "free fix" - I'd regard and hope that it was help from like-minded amateur self-fixers? I've done all of the diagnosis and investigative donkey work myself, and am only trying to share where I've got to for another pair of eyes to look at it, and hopefully nudge me in a different direction (if I am completely on the wrong track), or confirm if they think I'm on the right track - isn't that why this forum is here? Sincere apols again if I've inadvertently got the wrong end of the stick here.

I'm applying the logic to the information that I've uncovered myself already, on the basis that it could likely be the actuator that is sticking, the N75 solenoid that is faulty, or the map sensor reading the boost pressure incorrectly. I've largely discounted the latter two, as if either of these were faulty, I'd expect to see a separate fault code relating to either of those units. Also, if they were faulty, I'd expect (from my limited logic) for the overboost (actual pressure) to be there from the very beginning of the rev range, rather than only really starting to go well out of kilter with the specified pressure figure at about 2,800 RPM or so. Is this logic sound?

Many thanks in advance for anyone that is able to assist in any way...
 

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I've been trying to use the Ross-Tech forum for months, having registered the VCDS cable with the website as soon as I got it. I've done all of those steps, but am still not able to use the forums, despite their website confirming that my VCDS cable is accepted as being registered! A number of emails to the forum mods, with no response, and I've given up with them. Hence me trying to uncover the root cause of my problem here.
Did you register online VCDS Dongle Registration where you can copy and paste the serial from the About box? Do you have the older VCDS or the newer HEX-NET or HEX-V2 these are slightly different.

Can you log into the Ross-Tech forum? If so then find Uwe and send him a PM explaining you problems with registration. If you can't log in and PM Uwe send me a conversation with all your details, username, serial number and I will PM Uwe and ask him way you can't use the forum.
 

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Discussion Starter #6
Did you register online VCDS Dongle Registration where you can copy and paste the serial from the About box? Do you have the older VCDS or the newer HEX-NET or HEX-V2 these are slightly different.

Can you log into the Ross-Tech forum? If so then find Uwe and send him a PM explaining you problems with registration. If you can't log in and PM Uwe send me a conversation with all your details, username, serial number and I will PM Uwe and ask him way you can't use the forum.
Yes, the dongle was validated way back in August last year, and received an "account validated" email confirmation from Ross-Tech.

Yes, I can login to the Ross-Tech forums, but whenever you try and post or start a new thread, it throws up a "you don't have sufficient privileges or your account is awaiting activation" message, and I can go no further.

I've used the "Contact Us" form on the RT website three times to report the registration issue - no response. I gave up. There is no published email that I can find to be able to contact them directly to report the same error in a slightly more direct way. You don't get any sort of email to confirm that the webform has even been successful - no idea if it even works, but you're stuck with how they control contact to them.

Thank you for your offer of help to PM Uwe - appreciated.

What did you make of my engine/turbo issue?
 
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