Where to Start? Limp Mode, P2128/P2138, intermittent no RPM. MIL/ESC/EPC dash lights

[2slow2race]

Thanks in advance for any advice on where to start.

Where to Start? 2009 B8 A4 Avant CAEB 2.0 , 164480 miles. Limp Mode, P2128/P2138, intermittent no RPM after start.

Multiple dash lights Check Engine, Parking Brake Malfunction, Electronic Stabilization Control(ESC), EPC. ESP Fault when starting

Here's what I see when I scan it:

Engine
4698 - Function Restriction due to Faults in Other Modules U1113 00 [039]
2816 - Accelerator Position Sensor 2 (G185)
P2128 00 [167] - Signal too High

4667 - Accelerator Position Sensors (G79) / (G185)
P2138 00 [167] - Implausible Correlation

ABS
00473 - Control Module for Elect. Park/Hand Brake (J540)
013 - Check DTC Memory
01314 - Engine Control Module
013 - Check DTC Memory

Parking Brake
01314 - Engine Control Module
013 - Check DTC Memory - MIL ON

So far - Replaced accelerator pedal thinking it may take care of P2128/P2138. P2128 went away, then came back. Initially only went to 3 mph even when floored. Now can go up to 35 mph, but no faster. Intermittent - after starting engine, no RPM when I press on pedal.

Also replaced/recoded battery thinking it was bad (low voltage)


Here's the VCDS Scan

Chassis Type: 8K-AU48 (8T0)
Scan: 01 02 03 05 07 08 09 0E 0F 10 14 15 16 17 19 1B 1E 36 37 3C
42 46 47 52 53 55 56 62 65 67 6C 6D 72 77

Mileage: 264710km-164483miles

01-Engine -- Status: Malfunction 0010
03-ABS Brakes -- Status: Malfunction 0010
53-Parking Brake -- Status: Malfunction 0010

---------------------------------------------------------------
Address 01: Engine (DL0MA-CAEB) Labels:| 06H-907-115-CAB.clb
Part No SW: 8K2 907 115 AL HW: 8K2 907 115 D
Component: 2.0l R4/4V TF H14 0001
Revision: E1H14---
Coding: 010C010A190F0160
Shop #: WSC 11091 002 1048576
ASAM Dataset: EV_ECM20TFS0118K2907115AL 001001
ROD: EV_ECM20TFS0118K2907115AL.rod
VCID: 79ACE4337958720315D-802C

3 Faults Found:
4698 - Function Restriction due to Faults in Other Modules
U1113 00 [039] - -
Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 6
Fault Frequency: 4
Mileage: 264711 km
Date: 2020.11.04
Time: 11:15:55

Engine speed: 0.00 /min
Normed load value: 0.0 %
Vehicle speed: 0 km/h
Coolant temperature: 97 °C
Intake air temperature: 43 °C
Ambient air pressure: 990 mbar
Voltage terminal 30: 11.779 V
Unlearning counter according OBD: 40

2816 - Accelerator Position Sensor 2 (G185)
P2128 00 [167] - Signal too High
MIL ON - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 4
Mileage: 264711 km
Date: 2020.11.04
Time: 11:15:56

Engine speed: 0.00 /min
Normed load value: 0.0 %
Vehicle speed: 0 km/h
Coolant temperature: 96 °C
Intake air temperature: 43 °C
Ambient air pressure: 990 mbar
Voltage terminal 30: 11.779 V
Unlearning counter according OBD: 40

4667 - Accelerator Position Sensors (G79) / (G185)
P2138 00 [167] - Implausible Correlation
MIL ON - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 2
Mileage: 264711 km
Date: 2020.11.04
Time: 11:15:55

Engine speed: 0.00 /min
Normed load value: 0.0 %
Vehicle speed: 0 km/h
Coolant temperature: 96 °C
Intake air temperature: 43 °C
Ambient air pressure: 990 mbar
Voltage terminal 30: 11.779 V
Unlearning counter according OBD: 40

Readiness: 1110 0101

---------------------------------------------------------------
Address 03: ABS Brakes (J104) Labels:. 8K0-907-379-V1.clb
Part No SW: 8K0 907 379 AD HW: 8K0 907 379 AD
Component: ESP8 quattro H04 0060
Revision: -------- Serial number: --------------
Coding: 152500
Shop #: WSC 06335 000 00000
VCID: 7BA0FE3B73E44013071-802E

2 Faults Found:
00473 - Control Module for Elect. Park/Hand Brake (J540)
013 - Check DTC Memory
Freeze Frame:
Fault Status: 01101101
Fault Priority: 6
Fault Frequency: 1
Reset counter: 187
Mileage: 264711 km
Time Indication: 0
Date: 2020.11.04
Time: 11:17:45

Freeze Frame:
Hex Value: 0x0000
Hex Value: 0x0280
Hex Value: 0x0016
Hex Value: 0x0295
Hex Value: 0x00FF

01314 - Engine Control Module
013 - Check DTC Memory
Freeze Frame:
Fault Status: 01101101
Fault Priority: 6
Fault Frequency: 1
Reset counter: 187
Mileage: 264711 km
Time Indication: 0
Date: 2020.11.04
Time: 11:30:05

Freeze Frame:
Hex Value: 0x0000
Hex Value: 0x0782
Hex Value: 0x000A
Hex Value: 0x6393
Hex Value: 0x00FF

---------------------------------------------------------------
Address 53: Parking Brake (J540) Labels: 8K0-907-801-V1.clb
Part No SW: 8K0 907 801 E HW: 8K0 907 801 E
Component: EPB Audi B8 H05 0060
Revision: 00000003 Serial number: 00000000209661
Shop #: WSC 00000 000 00000
VCID: 313C1C13E1287A43EDD-8064

1 Fault Found:
01314 - Engine Control Module
013 - Check DTC Memory - MIL ON
Freeze Frame:
Fault Status: 11101101
Fault Priority: 4
Fault Frequency: 1
Reset counter: 187
Mileage: 264711 km
Time Indication: 0
Date: 2020.11.04
Time: 11:15:51

Freeze Frame:
Voltage: 11.90 V
Count: 58
Speed: 0.0 km/h
Hex Value: 0x0273
Hex Value: 0x0001
Hex Value: 0x1010

[Smac770]

So it says the G185 voltage reading is too high. The ECM supplies 5v and ground to the sensor, and reads the voltage "in the middle". It's just a potentiometer. There's an additional resistor in line with the G185, so it's reading should be a set value less than the reading from G79.

When you replaced your accelerator pedal, you notice a 6-pin connector on it. Did you test the voltages on the plug to see if 5v and ground was as expected? With the plug installed, when you press on the pedal, what values do you see for accel pedal 1 and accel pedal 2 in the advanced measuring values? IDE00392 and IDE00393. You do not need the engine running for this, but you do need ignition on.

Did you validate the wiring from the G79/G185 to the ECM? The wires pass through a 17-pin plug at the base of the A-pillar and then a 17-pin plug into the ECM box.

T6ag/1 - brown/green - T17e/1 - T17r/1 - ECM
T6ag/2 - yellow/violet - T17e/2 - T17r/2 - ECM
T6ag/3 - brown/red - T17e/3 - T17r/3 - ECM
T6ag/4 - yellow/blue - T17e/4 - T17r/4 - ECM
T6ag/5 - yellow/gray - T17e/5 - T17r/5 - ECM
T6ag/6 - brown - T17e/6 - T17r/6 - ECM

I would expect 5v on 1 and 2, ground on 4 and 6, and the readings you see in VCDS on 3 and 5. I can't guarantee this; just seems to be what to expect based on the docs I can read. Such that it seems: G79 is 5v on 2, ground on 4, reading on 3. G185 is 5v on 1, ground on 6, reading on 4.

T6ag is the plug at the accelerator pedal. T17e is the red plug in the middle of the bottom row at the base of the A-pillar. T17r is the white plug at the forward left in the ECM box.

[Theiceman]

Yeah definitely it thinks the pedal.is floored...
I have vcds on my 8.5 if you want me to log something to compare.

But smac is right on. When you press the pedal you should see the signal voltage increase

Sent from my SM-G973W using Audizine Forum mobile app

[2slow2race]

Resolved - it was the EPC - I had 8K0907801E, but it was superseded by 8K0907801H. Easy swap out. The connector had sort of a slide lock lever release. Thanks to SMAC and Iceman for chiming in.

[Smac770]

Doesn't really make any sense there. If the J540 had died, the scan tool should not have been able to communicate with it. That the part revision has rolled from E to H over time is not particularly significant. My '09 still runs fine with E. And while a loose connector would explain the ABS-ESP & EPB DTCs, it would have no reason to have any interaction with the EPC system. There's no chance of any electrical or wiring interaction between those aspects.

ESP/ESC = electronic stability program/control, part of the ABS system
EPB = electronic parking brake
EPC = electronic power control, the accelerator pedal and throttle body control, the throttle by wire, not the parking brake

Resolved is resolved, but something incomplete about the overall understanding of that now past event.

[2slow2race]

Thanks SMAC - you're right, there's something else going on. Appreciate your guidance and insight. Anyway, it worked fine for day, now dash lights are back on again (but didn't drive it, so not sure if it's still limp mode). Yesterday after replacing J540 - parking brake was flashing. Reset codes - no longer flashing and all the other dash lights were gone. Took it for a 10 mile drive, no lights, beeps, easily brought up to speed, instant response from pedal with no high RPMs. That's why I thought it was resolved. Maybe needs to be warmed up? Won't have a chance to take a look again until the weekend.

I haven't done much with the wiring side, so all new to me. You mentioned this in Post #2 - When you replaced your accelerator pedal, you notice a 6-pin connector on it. Did you test the voltages on the plug to see if 5v and ground was as expected? With the plug installed, when you press on the pedal, what values do you see for accel pedal 1 and accel pedal 2 in the advanced measuring values? IDE00392 and IDE00393. You do not need the engine running for this, but you do need ignition on.
* how do you get to IDE00392 and IDE00393 *

Did you validate the wiring from the G79/G185 to the ECM? The wires pass through a 17-pin plug at the base of the A-pillar and then a 17-pin plug into the ECM box.
* Where is the 17-pin plug? Do you access it from the driver side fuse panel? *

[Smac770]

IDExxxxx are measuring values, accessed under Advanced Measuring Values in the ECM.

https://www.ross-tech.com/vcds/tour/main_screen.php
select select under select control module

https://www.ross-tech.com/vcds/tour/scm_screen.php
select engine

https://www.ross-tech.com/vcds/tour/open_screen.php
select advanced measuring values

https://www.ross-tech.com/vcds/tour/adv-meas-blocks.php
search on IDE0039 and pick the two relevant values

then watch the values as you depress the accelerator pedal

As for the wiring path, I've noted where the two 17-pin plugs are located along the wiring path. One at the base of the A-pillar behind the kick panel and one in the ECM box.

How to remove the kick panel to access the terminal block at the base of the A-pillar: https://www.audizine.com/forum/showt...-panel-removal
It looks something like this behind all the plastic: https://www.audiworld.com/tech/pics/..._0946-edit.jpg

ECM box: https://forums.quattroworld.com/a5/msgs/7356.phtml
It's under the plenum cover, and you'll also have to remove the windshield washer fluid filler neck as the box is right under that.

https://www.audiforums.com/forum/att...b8-fusebox.jpg
You can see the white 17-pin in that pic.

[2slow2race]

SMAC - WOW - thanks so much for all the links. You are such a GREAT resource! Will update when I get a chance to look at it again. Thanks again for ALL your help!