Unexplainable limp mode

[Rabattie]

Hi all, I’m new to this forum (as a member, have been reading/googling/loving for much longer!) so apologies beforehand if I’m breaking any rules/best practices!

I took a big risky plunge by buying a private entry copart Audi A4 B9, no damage but numerous mechanical issues as that was more or less as far as my budget stretched and the A4 B9 is just too amazing allround of a car to pass on.

Amongst many other errors, it showed “dpf restricted”, and thus was in limp mode, was able to undo limp mode by unplugging the 3 sensors that on the front side of the engine on top of each other and then tried to do multiple motorway regens, parked ones with and without dpf foam spray but with no luck. Car drove pretty much bang on without the sensors connected btw.

Decided to gut dpf, delete egr and dpf and map stage 1 with a renowned local business that has done many of these before and very good Google reviews as well.

Here’s the mystery, the car is still in limp mode, cel is off and dpf restricted error is gone, but now I can’t even get the car out of limp mode anymore by unplugging those 3 sensors..

I’m far from an expert but the below errors (no vagcom present yet sorry) dont really look like reasons for a limp mode or do they? Not sure what the ecu ones are tried Googling but not getting far:


Car Scanner ELM OBD2
DTC report
Selected brand: Audi
VIN: WAUZZZF44HA149882

============1==============
8782084
Raw code: 860104
ECU: 19. CAN Gateway
Status: Test failed, Confirmed
Audi: B114E96: tiptronic downshift button on steering wheel
Internal malfunction
Status bits: 1
Priority: 4
Frequency: 1
Unlearning index: 76
Odometer: 106164 km
Date, time: 2022.07.29 20:51:34
============2==============
8782085
Raw code: 860105
ECU: 19. CAN Gateway
Status: Test failed, Confirmed
Audi: B114F96: tiptronic upshift button on steering wheel
Internal malfunction
Status bits: 1
Priority: 4
Frequency: 1
Unlearning index: 76
Odometer: 106164 km
Date, time: 2022.07.29 20:51:34
============3==============
16646145
Raw code: FE0001
ECU: 19. CAN Gateway
Status: Test failed, Confirmed
Status bits: 1
Priority: 6
Frequency: 64
Unlearning index: 76
Odometer: 106164 km
Date, time: 2022.07.29 20:51:34
============4==============
23810
Raw code: 005D02
ECU: 01. Engine control unit
Status: Test failed (current drive cycle), Pending, Test failed since last DTC clear
Status bits: 1
Priority: 2
Frequency: 2
Unlearning index: 255
Odometer: 106164 km
Date, time: 2022.07.29 20:52:31
============5==============
23812
Raw code: 005D04
ECU: 01. Engine control unit
Status: Test failed (current drive cycle), Pending, Test failed since last DTC clear
Status bits: 1
Priority: 2
Frequency: 3
Unlearning index: 255
Odometer: 106164 km
Date, time: 2022.07.29 20:51:25
============6==============
23821
Raw code: 005D0D
ECU: 01. Engine control unit
Status: Test failed (current drive cycle), Pending, Test failed since last DTC clear
Status bits: 1
Priority: 2
Frequency: 2
Unlearning index: 255
Odometer: 106164 km
Date, time: 2022.07.29 20:51:52
============7==============
4901
Raw code: 001325
ECU: 01. Engine control unit
Status: Test failed, Test failed (current drive cycle), Pending, Test failed since last DTC clear
Audi: P158800: Engine mounting valve
Open circuit
Audi: Knock control cylinder 1 control limit reached
Status bits: 1
Priority: 2
Frequency: 1
Unlearning index: 255
Odometer: 106164 km
Date, time: 2022.07.29 20:51:21
============8==============
25399
Raw code: 006337
ECU: 01. Engine control unit
Status: Test failed, Test failed (current drive cycle), Pending, Test failed since last DTC clear
Audi: U10BA00: Local data bus
No communication
Status bits: 1
Priority: 2
Frequency: 1
Unlearning index: 255
Odometer: 106164 km
Date, time: 2022.07.29 20:51:21
============9==============
65544
Raw code: 010008
ECU: 08. Heater and climate
Status: Test failed, Confirmed
Audi A1 2019; A3 2013, Q2 2017, A3 USA/ CAN 2013, TT USA/ CAN 2015, Q3 2019, TT 2015; A4 2016, A5 2017, Q5 2017, A4 USA/ CAN 2016, Audi A5 USA / CAN 2016, Q5 USA/ CAN 2017; Q7 2016; R8 2015: B131207: Button(s) in operating unit
mechanical malfunction
Audi A1 2019: C103429: Left front level control system sensor
Implausible signal
Audi Q8 2018, A6 2018, A7 2018, A6 USA/ CAN 2018, A7 USA/ CAN 2018, Q8 USA 2019 >, e - tron 2019 > e - tron USA 2019 >; A8 2018; Q7 2016: C12DEF0: Nightview assist
Status feedback for HMI implausible
Audi: B139D29: Switch for folding top stored, left
Implausible signal
Status bits: 1
Priority: 5
Frequency: 1
Unlearning index: 76
Odometer: 106167 km
Date, time: 2022.07.30 12:29:53
============10==============
65619
Raw code: 010053
ECU: 09. Onboard supply control unit
Status: Test failed, Confirmed
Audi A4 2016, A5 2017, Q5 2017, A4 USA/ CAN 2016, Audi A5 USA / CAN 2016, Q5 USA/ CAN 2017; Q8 2018, A6 2018, A7 2018, A6 USA/ CAN 2018, A7 USA/ CAN 2018, Q8 USA 2019 >, e - tron 2019 > e - tron USA 2019 >; A8 2018; Q7 2016: B121715: Left low beam headlamp bulb
Open circuit/short circuit to B
Audi Q8 2018, A6 2018, A7 2018, A6 USA/ CAN 2018, A7 USA/ CAN 2018, Q8 USA 2019 >, e - tron 2019 > e - tron USA 2019 >: B196307: Left rear seat backrest fan 1
mechanical malfunction
Status bits: 1
Priority: 5
Frequency: 1
Unlearning index: 76
Odometer: 106167 km
Date, time: 2022.07.29 21:01:48
============11==============
9496851
Raw code: 90E913
ECU: 15. SRS
Status: Test failed, Confirmed, Warning indicator requested
Audi: B10E913: Center pedestrian protection crash sensor
Open circuit
Status bits: 1
Priority: 2
Frequency: 1
Unlearning index: 255
Odometer: 105869 km
Date, time: 2022.07.16 14:18:03
============12==============
9682162
Raw code: 93BCF2
ECU: 15. SRS[Archive (inactive)]
Status: Confirmed
Audi: B13BCF2: Multiple collision brake
No function

============13==============
196660
Raw code: 030034
ECU: 52. Front passenger door electronics
Status: Test failed, Confirmed
Audi A3 2020; A4 2016, A5 2017, Q5 2017, A4 USA/ CAN 2016, Audi A5 USA / CAN 2016, Q5 USA/ CAN 2017; Q8 2018, A6 2018, A7 2018, A6 USA/ CAN 2018, A7 USA/ CAN 2018, Q8 USA 2019 >, e - tron 2019 > e - tron USA 2019 >; A8 2018; Q7 2016: B148754: Motor for window regulator
No basic setting
Audi A4 2016, A5 2017, Q5 2017, A4 USA/ CAN 2016, Audi A5 USA / CAN 2016, Q5 USA/ CAN 2017; Q8 2018, A6 2018, A7 2018, A6 USA/ CAN 2018, A7 USA/ CAN 2018, Q8 USA 2019 >, e - tron 2019 > e - tron USA 2019 >; A8 2018; Q7 2016: B107914: Right rear park assist sensors
Open circuit/short circuit to ground
Status bits: 1
Priority: 5
Frequency: 1
Unlearning index: 76
Odometer: 106164 km
Date, time: 2022.07.29 20:51:39
============14==============
1123714
Raw code: 112582
ECU: A5. Front Assistant A5 (UDS)
Status: Test failed, Confirmed
Status bits: 1
Priority: 6
Frequency: 1
Unlearning index: 76
Odometer: 106164 km
Date, time: 2022.07.29 20:51:39
============15==============
1123591
Raw code: 112507
ECU: A5. Front Assistant A5 (UDS)
Status: Test failed, Confirmed
Status bits: 1
Priority: 6
Frequency: 49
Unlearning index: 76
Odometer: 106164 km
Date, time: 2022.07.29 20:51:34
============16==============
65587
Raw code: 010033
ECU: 46. Comfort unit
Status: Test failed, Confirmed
Audi A1 2019; A3 2013, Q2 2017, A3 USA/ CAN 2013, TT USA/ CAN 2015, Q3 2019, TT 2015: B148707: Motor for window regulator
mechanical malfunction
Audi A4 2016, A5 2017, Q5 2017, A4 USA/ CAN 2016, Audi A5 USA / CAN 2016, Q5 USA/ CAN 2017; Q8 2018, A6 2018, A7 2018, A6 USA/ CAN 2018, A7 USA/ CAN 2018, Q8 USA 2019 >, e - tron 2019 > e - tron USA 2019 >; A8 2018; Q7 2016: B12D015: Left turn signal light bulb
Open circuit/short circuit to B
Audi A4 2016, A5 2017, Q5 2017, A4 USA/ CAN 2016, Audi A5 USA / CAN 2016, Q5 USA/ CAN 2017; Q8 2018, A6 2018, A7 2018, A6 USA/ CAN 2018, A7 USA/ CAN 2018, Q8 USA 2019 >, e - tron 2019 > e - tron USA 2019 >; A8 2018: B131329: Signal for brake lamp
Implausible signal
Audi Q8 2018, A6 2018, A7 2018, A6 USA/ CAN 2018, A7 USA/ CAN 2018, Q8 USA 2019 >, e - tron 2019 > e - tron USA 2019 >: B10E601: Position sensor in right rear upper body vent
Electrical error

The errors for steering wheel and doors is from a (badly done?) black edition retrofit, steering wheel is from an automatic whereas mine is manual and is originally a Sport.

Anyone spot anything that could explain the limp mode?

 

[Booboo]

Holy Moly

 

[spartacus68]

What’s the history of the car? That’s a lot of errors for no damage?

Knock control on cylinder 1 control limit reached is worth investigating. Not sure what you’re using to scan the car but you will need VCDS to chase down these errors, as you may need to measure voltage, timing, etc.

 

[Rabattie]

What’s the history of the car? That’s a lot of errors for no damage?

Knock control on cylinder 1 control limit reached is worth investigating. Not sure what you’re using to scan the car but you will need VCDS to chase down these errors, as you may need to measure voltage, timing, etc.

It’s a previous Cat S so definitely had some sort of a hit in the past, wasn’t after a perfect B9 you see just something that’s be worth investing a bit in to get it driving.

As the Knock control is part of the same error as the engine mounting valve I thought it’d be linked to that. The mounting valve has no cable going into the sensor, and nowhere could I find a loose cable so that’s one of the mysteries but I understood that mounting valves shouldn’t be able to cause a limp mode?

I use car scanner pro for the fault codes which is meant to be able to measure anything there is to be measured but I’m aware that a 50£ device is not the same as 200£.. when you say measure voltage what would you advise me to measure based on that knock code?

 

[Rabattie]

What’s the history of the car? That’s a lot of errors for no damage?

Knock control on cylinder 1 control limit reached is worth investigating. Not sure what you’re using to scan the car but you will need VCDS to chase down these errors, as you may need to measure voltage, timing, etc.

Bit confused now as after googling Diesel engines don’t have a knock sensor? So I guess it’s just an alternative description of that same fault code for the engine mount?

 

[spartacus 68]

You can get yourself a 10 VIN VCDS kit for £300 if you have a laptop to run it from? I'd clear all the DTC errors and then go from there, otherwise you're going to chase your tail. It's a handy bit of kit from priming the fuel pump to disabling the rear parking brake if you're swapping out discs and pads. I even used it to switch on rear LED like to come on with front DRLs and tacho sweep on start-up, plus countless other fixes.

I hadn't heard of a knock sensor either - until I'd searched, but it may share the same generic name depending on your scan device, which could be linked to a sensor on the block, speed sensor, etc. Anyway - it's like hunting for a needle in a haystack until you get the proper VAG fault code.

I see your engine is a DETA 140kw.

 

[Rabattie]

You can get yourself a 10 VIN VCDS kit for £300 if you have a laptop to run it from? I'd clear all the DTC errors and then go from there, otherwise you're going to chase your tail. It's a handy bit of kit from priming the fuel pump to disabling the rear parking brake if you're swapping out discs and pads. I even used it to switch on rear LED like to come on with front DRLs and tacho sweep on start-up, plus countless other fixes.

I hadn't heard of a knock sensor either - until I'd searched, but it may share the same generic name depending on your scan device, which could be linked to a sensor on the block, speed sensor, etc. Anyway - it's like hunting for a needle in a haystack until you get the proper VAG fault code.

I see your engine is a DETA 140kw.

That’s the nice thing about Car Scanner Pro, I can do all that and more either through long coding or through “apps” similar to obd 11.. but I guess when it comes down to proper diagnostics it’s no match for VCDS I won’t argue with that.

Yes it is the DETA engine indeed, I’m getting the car booked in at a local garage whom, I believe, have VCDS and hopefully they should be able to shed light on the reason for limp mode.

Know it’s probably not wise but I’ve driven the car for over 50 miles in limp mode speeds (flat ground) going to 40/50mph and, far as you could say it of a car in limp mode, the engine sounds/feels as fine as can be with an engine mount causing vibrations at idle speed. Hoping for something not too serious..