EGR Valve Fault

[Klaus Ludwig]

A friend has a UK B6 VW Passat (manufactured 2009). Recently it has had an engine warning light come up on the dash. We connected up my VCDS and found that there was an EGR valve fault.

The fault indicated on VCDS was:-

001027 - EGR Valve (N18)

P0403 - 000 - Malfunction



I have attached an auto-scan taken after the engine fault light came on:-

Sunday,17,October,2021,16:20:30:27553

VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64

VCDS Version: 21.9.0.2 (x64) HEX-V2 CB: 0.4555.4

Data version: 20210903 DS330.0

www.Ross-Tech.com





VIN: WVWZZZ3CZ9E098608 License Plate:

Mileage: 309650km-192407mi Repair Order:







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

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





Chassis Type: 3C-VW46 (3C0)

Scan: 01 03 08 09 15 16 17 19 25 37 42 44 46 52 53 56 6C



VIN: WVWZZZ3CZ9E098608 Mileage: 309650km-192407miles



01-Engine -- Status: Malfunction 0010

03-ABS Brakes -- Status: OK 0000

04-Steering Angle -- Status: OK 0000

08-Auto HVAC -- Status: OK 0000

09-Cent. Elect. -- Status: OK 0000

15-Airbags -- Status: OK 0000

16-Steering wheel -- Status: OK 0000

17-Instruments -- Status: OK 0000

19-CAN Gateway -- Status: OK 0000

25-Immobilizer -- Status: Malfunction 0010

37-Navigation -- Status: Malfunction 0010

42-Door Elect, Driver -- Status: OK 0000

44-Steering Assist -- Status: Malfunction 0010

46-Central Conv. -- Status: Malfunction 0010

52-Door Elect, Pass. -- Status: OK 0000

53-Parking Brake -- Status: Malfunction 0010

56-Radio -- Status: Malfunction 0010

6C-Back-up Cam. -- Status: OK 0000

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

Address 01: Engine (CBD) Labels: 03L-906-022-CBA.clb

Part No SW: 03L 906 022 BT HW: 03L 907 309

Component: R4 2,0L EDC 0000SG 6214

Revision: 13H01--- Serial number: VWZCZ000000000

Coding: 0000071

Shop #: WSC 00363 210 85044

VCID: 78AAE15AFED5F1DB9F1-802C

VINID: 9E69EAAAA0D3A8954024818020F8E835AA



2 Faults Found:

001299 - Incorrect Immobilizer Key

P0513 - 000 - - Intermittent

Freeze Frame:

Fault Status: 00100000

Fault Priority: 2

Fault Frequency: 2

Reset counter: 255

Mileage: 309476 km

Time Indication: 0

Date: 2016.03.09

Time: 21:26:36



Freeze Frame:

RPM: 989 /min

Speed: 0.0 km/h

Voltage: 11.63 V

Absolute Pres.: 1009.8 mbar

Absolute Pres.: 969.0 mbar

Temperature: 18.9∞C

Temperature: 18.9∞C



001027 - EGR Valve (N18)

P0403 - 000 - Malfunction

Freeze Frame:

Fault Status: 01100000

Fault Priority: 2

Fault Frequency: 1

Reset counter: 255

Mileage: 309648 km

Time Indication: 0

Date: 2016.03.09

Time: 07:37:04



Freeze Frame:

RPM: 1702 /min

Speed: 42.0 km/h

Load: 0.0 %

Load: 16.9 %

Lambda: 27.6 %

Mass Air / Rev.: 275.0 mg/str

Temperature: 81.0∞C



Readiness: 0 0 0 0 0



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

Address 03: ABS Brakes Labels:. 3C0-614-109-C4.clb

Part No SW: 3C0 614 109 T HW: 3C0 614 109 T

Component: J104 C4 440 V2 0013

Revision: --025--- Serial number: 00000786438999

Coding: 0001286

Shop #: WSC 05311 000 00000

VCID: 2F381A064B1BF6630EB-807A



No fault code found.



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

Address 08: Auto HVAC Labels: 1K0-820-047.lbl

Part No SW: 1K0 820 047 JD HW: 1K0 820 047 JD

Component: Climatic PQ35 143 1313

Revision: 00143033 Serial number: 00000000000000

Shop #: WSC 00000 000 00000

VCID: 6FB8DA068B9BB6634EB-803A



No fault code found.



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

Address 09: Cent. Elect. Labels:. 3C0-937-049-30-M.lbl

Part No SW: 3C8 937 049 D HW: 3C8 937 049 D

Component: Bordnetz-SG H54 2602

Revision: 00H54000 Serial number: 00000009125181

Coding: 00880F0700041A00470A00000F000000000859435C000120000000000000

Shop #: WSC 05124 000 00000

VCID: 323E13725829DB8B615-8066



Subsystem 1 - Part No: 3C2 955 119 B Labels: 1KX-955-119.CLB

Component: Wischer 201108 022 0601

Coding: 00046997

Shop #: WSC 05124



No fault code found.



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

Address 15: Airbags Labels: 5N0-959-655.lbl

Part No SW: 5N0 959 655 A HW: 5N0 959 655 A

Component: J234__00Q VW10 HI 1815

Revision: 19013000 Serial number: 0039DPQZAV1O

Coding: 0012369

Shop #: WSC 05311 000 00000

VCID: 3B203E568F631AC3B23-806E



Subsystem 1 - Serial number: 6333FTS691633018



Subsystem 2 - Serial number: 6343FTS635553408



Subsystem 3 - Serial number: 6353ETS6R6PVVVNR



Subsystem 4 - Serial number: 6363ETS6RQ45V5KJ



Subsystem 5 - Serial number: 00000000000000000



Subsystem 6 - Serial number: 00000000000000000



No fault code found.



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

Address 16: Steering wheel Labels: 3C0-953-549-SW25.lbl

Part No SW: 3C0 953 549 AT HW: 3C0 953 549 AT

Component: J0527 0030

Revision: 00034000 Serial number: 3C9953507CE

Coding: 0000004

Shop #: WSC 05314 000 00000

VCID: 7EA6F742DCF1CFEBD5D-802A



No fault code found.



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

Address 17: Instruments (J285) Labels:| 3C8-920-xxx-17.clb-SRI1

Part No SW: 3C0 920 971 R HW: 3C0 920 971 R

Component: KOMBI H04 0107

Serial number: 00000000000000

Coding: 460F00

Shop #: WSC 05314 115 00000

ASAM Dataset: EV_Kombi_UDS_VDD_RM09 A04040

ROD: EV_Kombi_UDS_VDD_RM09_004_VW46.rod

VCID: 3432156AAEBDD5BB739-8060



No fault code found.



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

Address 19: CAN Gateway Labels:. 3C0-907-530-V3.clb

Part No SW: 3C0 907 530 L HW: 3C0 907 951

Component: J533__Gateway H13 0152

Revision: H13 Serial number: 3300P08C0804AD

Coding: F9801F06404202002003

Shop #: WSC 05314 000 00000

VCID: 2A0E0B1270F9934BD95-807E



No fault code found.



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

Address 25: Immobilizer Labels: 3C0-959-433-25.clb

Part No SW: 3C0 959 433 AQ HW: 3C0 959 433 AQ

Component: IMMO 044 0383

Revision: 00044000 Serial number: VWZCZ000000000

Shop #: WSC 131071 1023 2097151

VCID: 79ACE45EC5DFE8D3E0F-802C



Subsystem 1 - Part No: 3C0 905 861 G

Component: ELV 027 0380

3C0905861G ELV 027 0380



1 Fault Found:

02861 - Electronic Steering Column Lock Check Sum Error

008 - Implausible Signal - Intermittent

Freeze Frame:

Fault Status: 00101000

Fault Priority: 4

Fault Frequency: 2

Reset counter: 182

Mileage: 308037 km

Time Indication: 0

Date: 2016.03.09

Time: 21:08:50





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

Address 37: Navigation (J0506) Labels:. 1T0-035-680.clb

Part No SW: 1T0 035 680 L HW: 1T0 035 680 BX

Component: RNS-MID H03 5238

Revision: AB001001 Serial number: VWZ6Z7H6306026

Coding: 00010400000000000000

Shop #: WSC 12345 123 12345

VCID: 37282266BF4B3EA356B-8062



Subsystem 1 - Part No: 1T0 919 859 B

Component: EU West V16 8536



1 Fault Found:

00823 - Line-Output; Front Left

007 - Short to Ground

Freeze Frame:

Fault Status: 01100111

Fault Priority: 5

Fault Frequency: 254

Reset counter: 151

Mileage: 293872 km

Time Indication: 0





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

Address 42: Door Elect, Driver Labels:. 1K0-959-701-MIN3.clb

Part No SW: 1K0 959 701 AC HW: 1K0 959 793 N

Component: J386 TUER-SG FT 1518

Revision: 72009005 Serial number: 00000628989110

Coding: 0000565

Shop #: WSC 05311 000 00000

VCID: 6FB8DA068B9BB6634EB-803A



No fault code found.



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

Address 44: Steering Assist Labels: 1K0-909-14x-GEN3.clb

Part No: 1K0 909 144 E

Component: EPS_ZFLS Kl. 195 2501

Revision: 00H15000

Shop #: WSC 02069 000 90108

VCID: 2C020D0A7A0D8D7B2B9-8078



1 Fault Found:

00750 - Warning Lamp

013 - Check DTC Memory - Intermittent

Freeze Frame:

Fault Status: 00101101

Fault Priority: 2

Fault Frequency: 3

Reset counter: 201

Mileage: 302237 km

Time Indication: 0

Date: 2016.03.09

Time: 06:07:42



Freeze Frame:

Voltage: 11.38 V

DD

Temperature: 8.0∞C

RPM: 1229 /min

Speed: 0.0 km/h

Speed: 0.0 km/h

Count: 0





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

Address 46: Central Conv. Labels:. 3C0-959-433-46.clb

Part No SW: 3C0 959 433 AQ HW: 3C0 959 433 AQ

Component: KSG PQ46 ELV 044 0612

Revision: 00044000 Serial number: VWZCZ000000000

Coding: 0191020851030E763004941570085BCE103C01

Shop #: WSC 05311 000 00000

VCID: 79ACE45EC5DFE8D3E0F-802C



Subsystem 1 - Component: Sounder No Answer



Subsystem 2 - Part No: 3C0 951 171 C

Component: Neigungssensor 004 0611



Subsystem 3 - Part No: 3C0 951 171 C

Component: Innenraumueberw.004 0611



1 Fault Found:

01134 - Alarm Horn (H12)

004 - No Signal/Communication

Freeze Frame:

Fault Status: 01100100

Fault Priority: 4

Fault Frequency: 14

Reset counter: 168

Mileage: 302236 km

Time Indication: 0

Date: 2016.03.09

Time: 09:27:45





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

Address 52: Door Elect, Pass. Labels:. 1K0-959-702-MIN3.clb

Part No SW: 1K0 959 702 AC HW: 1K0 959 792 N

Component: J387 TUER-SG BT 1518

Revision: 72009005 Serial number: 00000513489111

Coding: 0000564

Shop #: WSC 05311 000 00000

VCID: 70BAD97A96A5A99B571-8024



No fault code found.



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

Address 53: Parking Brake Labels: 5N0-907-801.clb

Part No SW: 3C8 907 801 A HW: 3C8 907 801 A

Component: J540 EPB3 VW-10498 0003

Revision: 009 Serial number: 00000000217648

Coding: 0000057

Shop #: WSC 05311 000 00000

VCID: 280AF11A6EF5A15BCF1-807C



1 Fault Found:

03200 - Switch for Electric Parking Brake (E538)

012 - Electrical Fault in Circuit - Intermittent

Freeze Frame:

Fault Status: 00101100

Fault Priority: 2

Fault Frequency: 12

Reset counter: 171

Mileage: 307046 km

Time Indication: 0

Date: 2016.03.09

Time: 06:21:09



Freeze Frame:

Voltage: 9.70 V

Count: 93

Speed: 0.0 km/h

Hex Value: 0x12E1

Hex Value: 0x0001

Hex Value: 0x1010





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

Address 56: Radio (J0506) Labels:. 1T0-035-680.clb

Part No SW: 1T0 035 680 L HW: 1T0 035 680 BX

Component: RNS-MID H03 5238

Revision: AB001001 Serial number: VWZ6Z7H6306026

Coding: 00010400000000000000

Shop #: WSC 12345 123 12345

VCID: 37282266BF4B3EA356B-8062



Subsystem 1 - Part No: 1T0 919 859 B

Component: EU West V16 8536



1 Fault Found:

00823 - Line-Output; Front Left

007 - Short to Ground

Freeze Frame:

Fault Status: 01100111

Fault Priority: 5

Fault Frequency: 254

Reset counter: 151

Mileage: 293872 km

Time Indication: 0





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

Address 6C: Back-up Cam. Labels: 5N0-907-441.clb

Part No SW: 3C0 907 441 HW: 3C0 907 441

Component: J772__Rearview 0042

Revision: 00H05000 Serial number: PA8 J8X0064

Coding: 0000007

Shop #: WSC 05311 000 00000

VCID: 5F98AAC67B3B26E3FEB-800A



No fault code found.



End----(Elapsed Time: 01:09, VBatt start/end: 11.7V/11.7V. VIgn 11.7V)-----

We removed the EGR valve and cleaned it in an ultrasonic bath taking care to keep the electrics clear of the water. After plugging the valve in electrically we carried out a VCDS Output test on it. There was a high pitched buzzing sound each time the valve tried to open, but the valve barely moved (possibly only a fraction of a mm).

We removed the plastic gear case cover and operated the gears by hand. The valve lifted freely over its full stroke (at least an estimated 6mm) against firm spring pressure. We put the plastic gearcase cover back on and carried out the VCDS Output test again. Still the same. The valve barely moved.

We then carried out a Basic Setting on Group 123 (as indicated by the menu system for EGR valve basic setting). It appeared to attempt a calibration before Basic Setting automatically turned off. Again the valve barely moved.

The four fields in the Basic Settings window (Group 123) showed the following on completion of the calibration activity:- 0.0%, 00000100, 00000010, 0.684V

We noted that there is an EGR valve RESET function in the Adaptations menu. We did not activate this as we were uncertain of its purpose and whether its use would be appropriate.

Finally, we re-installed the EGR valve and cleared DTC’s. There are currently no engine faults showing on the auto-scan. We believe it is most likely that the EGR fault will soon re-appear.

• Should the EGR valve do a full stroke when tested using the VCDS Output test? We assume that it should.
• Any suggestions as to what we can do next to resolve our issue with the EGR valve?

 

[Crasher]

The EGR valve on this engine was a known failure and has been updated to new part number 03L 131 501 K

 

[Klaus Ludwig]

Thanks @Crasher for your input.



If anyone else has some more technical feedback or advice on our problem it would be VERY much appreciated.



The car owner (a close relative) has purchased a new EGR valve. This also has similar symptoms to the original EGR valve when tested using the VCDS output test. It barely opens and vibrates when it does so.



We have just tried putting 12v dc directly on the motor terminals of the original EGR valve with the valve on a bench and the valve opens fully. As the new valve behaves in a similar way to the original valve it is looking more and more likely that we have a wiring or ECU issue (and by wiring I am including harness plug/socket faults).



I believe the EGR valve motor is 12v dc pulse width modulated fed by 2 wires and that the feedback is 0.5 to 5V via a Hall Effect Sensor mounted inside the EGR valve assembly. There are 3 wires connected to the valve position sensor. (0, 5V and signal). We have confirmed that there is 5V relative to earth on one of the 3 wires going to the position sensor.



This may be important:- For info, when measuring voltage relative to the battery negative terminal on the two wires in the plug that fits onto the EGR valve we measured +12v on BOTH wires with the plug disconnected from the EGR valve.



Hoping that someone out there has some ideas that may help us.

 

[Crasher]

I suspect the problem is in the ECU, if there was something wrong with the 5v feed (yellow/blue to plug T6 pin 1) or the earth (brown/red to pin 3) you would expect codes in G81, G28, G69,G247 and G581. Test the continuity of the wires from the ECU to the EGR plug

Brown/white from the 60 pin plug at T6 pin 2, lilac/green T60/57 to T6/5 and blue/white T60/19 to T6/6. The 5v feed is from ECU T60/53 to T6/1, remember to disconnect G81, G28, G69,G247 and G581 to check the continuity. There is also the possibility that one of these devices is causing the problem. The 5v feed is from T60/25 to T6/1.

 

[Klaus Ludwig]

Thanks @Crasher. I will follow up on your advice and revert in due course. I don't suppose you (or anyone else) would know EXACTLY where I could get a wiring diagram to confirm ECU pins and harness plug pins etc. I downloaded a lot from ERWIN a few years ago, but looking through it I have not yet seen anything that I would call a wiring diagram unless I'm missing something. I have "Electrical System Workshop Manual" and "Electrical System General Information Workshop Manual" and lots more, but cannot find the relevant info. I'm not an auto electrician or any kind of electrician, but do have a general engineering background with general electrical experience of fault-finding (not on cars). If you are able to send me an electrical drawing that would be even better!

 

[Quintus Rotam]

. .. I have not yet seen anything that I would call a wiring diagram unless I'm missing something.

Perhaps it's called "Current Flow Diagram".

If you are able to send me an electrical drawing that would be even better!

Seems Crasher drew one with words, for a reason.

 

[Crasher]

Yes they are called Current Flow diagrams on erWin.

 

[Crasher]

Seems Crasher drew one with words, for a reason.

I like the way you put that.

 

[Klaus Ludwig]

Thanks! Different terminology to what I have experience of and for some reason I must have missed these. perhaps they are not in quite the same place as all the other documents I downloaded. I thought I had downloaded almost everything.

 

[Klaus Ludwig]

RE B6 2009 PASSAT

Hi @Crasher,

Very much appreciate the pin-out data for the ECU and EGR valve plug that you have given in words. I have tabulated my interpretation of it below. The car is at a relative’s address. I am not in front of it right now to refer to anything.

A few questions:-

• As per my table below you appear to have given two different terminals on the ECU for the 5V feed to the position sensor. Does that mean that only one of them is correct - and if so which?
• Which ECU pin if any is connected to EGR valve plug pin T6/2?
• Which ECU pin if any is connected to EGR valve plug pin T6/3?
• The EGR valve plug has two rows of 3 pins and the 2 motor pins were not adjacent to each other so may have been pins 4 & 6 rather than 5 and 6?

I looked in ERWIN again today and still could not find the “current flow diagrams” amongst the PDF’s of repair manuals, circuit diagrams etc . Are they in a diagnostics section of ERWIN?

I phoned VW Customer Service today and they were unable to help re ERWIN. I then phoned our local VW dealer service department and was told that they use ELSA and not ERWIN and would also not be sure where to find this info in ERWIN. If you know where to find it or can send it, it might give me a better overview. If not, then answers to my above 4 questions re the table below would be a big help.

Thanks in advance!



EGR PLUG ECU PLUG WIRE COLOUR FUNCTION

T6/1 FROMT60/53 OR T60/25 YELLOW/BLUE 5V FEED

T6/2 TO T60/?? BROWN/WHITE POSITION SENSOR SIGNAL

T6/3 FROM T60/?? BROWN/RED POSITION SENSOR EARTH

T6/4

T6/5 FROM T60/57 LILAC/GREEN EGR MOTOR

T6/6 FROM T60/19 BLUE/WHITE EGR MOTOR

 

[Klaus Ludwig]

EGR PLUG	ECU PLUG	WIRE COLOUR	FUNCTION
T6/1	FROM T60/53 OR T60/25	YELLOW/BLUE	5V FEED
T6/2	TO T60/??	BROWN/WHITE	POSITION SENSOR SIGNAL
T6/3	FROM T60/??	BROWN/RED	POSITION SENSOR EARTH
T6/4
T6/5	FROM T60/57	LILAC/GREEN	EGR VALVE MOTOR
T6/6	FROM T60/19	BLUE/WHITE	EGR VALVE MOTOR

 

[Crasher]

EGR PLUG	ECU PLUG	WIRE COLOUR/CSA	FUNCTION
T6/1	T60/25	YELLOW/BLUE 03.5mm	5V FEED the junction is known a D174 at which point the feed to G247 is a yellow/grey
T6/2	T60/4	BROWN/WHITE 1.0mm	I think this is the motor earth
T6/3	T60/53	BROWN/RED 0.35mm	POSITION SENSOR EARTH the junction is known as 85 where for G247 and G81 it changes to brown
T6/4 not used	NA	NA	none
T6/5	T60/57	LILAC/GREEN 0.35mm	Not sure about this
T6/6	T60/19	BLUE/WHITE 1.0mm	EGR VALVE MOTOR

 

[Klaus Ludwig]

Thanks @Crasher - much appreciated. We will progress as weather and other factors permit. Hopefully, we will be able to narrow the issue down to wiring or ECU fault.

 

[Klaus Ludwig]

Hi @Crasher,

Since found that the ERWIN document we needed had the word Climatronic in its title. I had ignored it assuming that it was something to do with air conditioning. Now know that it holds all the “current flow diagrams”

Your pin numbers for T6 & T60 were absolutely spot on. THANKS!!!

Today we carried out a continuity check on all 5 links between T6 and T60. All found to be OK. Also did a check to earth on these 5 using the megohm scale on a digital multimeter – all OK. Did not use insulation test mode as was afraid we might fry something.

Tested each of 5 pins on T6 to each and every pin on T60 to check for any possible issues. Only “crossovers” to other pins found were as follows:-

T6/1 to T60/53 was 655.2 ohms

T6/1 to T60/58 was 166.6 ohms

Note that you did mention that we would need to unplug G81, G28, G69, G247 and G581 for testing. We are in the process of finding what they are so that we can do that!

Looks now almost certain that our EGR valve issue is a fault with the ECU. We are planning to make arrangements to send it off for checking ASAP. Meanwhile we will disconnect whatever other devices are necessary (as per your advice) to confirm that the two crossover resistances from T6/1 disappear – once we figure out what those G numbers are!



Will let you know how things go.

 

[Quintus Rotam]

Note that you did mention that we would need to unplug G81, G28, G69, G247 and G581 for testing. We are in the process of finding what they are so that we can do that!

G28 Engine speed sender
G69 Throttle valve potentiometer
G81 Fuel temperature sender
G247 Fuel pressure sender
G581 Position sender for charge pressure positioner

 

[Klaus Ludwig]

Thanks for the confirmation @Quintus Rotam,
Already found their functions on the Current Flow Diagram very shortly after my last post, but as could not put my hands on them for real without a bit of a look around we have decided to send the ECU off for testing. Our tests to date indicate that the ECU is almost certainly where our issue is. We look forward to the feedback from our ECU specialist sometime next week.

 

[Crasher]

I have given up on ECU repair people, charlatans the lot of them.

 

[Klaus Ludwig]

Hi @Crasher,

As I believe you may have hinted at, I would have expected other faults to register on VCDS if any other actuators/sensors that share a feed with the EGR valve were faulty. As all continuity tests and tests to earth were good (even though I did not disconnect linked devices), it’s looking very much like an ECU fault.

The owner of the car is intending to use ecutesting.com

Assume that you have had a less than positive experience with ECU repair(s)?

I have absolutely no idea how much a new/exchange programmed ECU would cost from a main VW dealer. If you have a rough idea I would be interested to know. I believe parts and service departments of main dealers not open right now on a Saturday afternoon so cannot find out till Monday

What way forward would you choose if you don’t trust ECU repairers?

 

[Crasher]

Ohh God no, not him… just upt A610 from ere, notorious in the Nottingham motor trade. I did a court report for another garage over a DQ200 Mechatronic cock up they did.

 

[Klaus Ludwig]

Hi @Crasher,

Finally put my hands on the exact circuit flow diagram for our B6 Passat. I hadn’t realised that the wiring PDF document contained a number of different current flow diagrams depending on engine code. Our engine code is CBDC.

Before committing to use a “charlatan” and now with the correct Current Flow Diagram, armed with a better understanding of the circuit we tested T6/3 to earth and found no continuity. Testing T6/3 to T60/53 gives continuity.

As you have mentioned, half a dozen devices share a common earth. I see that this is via “85 Earth connection 1 , in engine compartment wiring harness”.

We currently have no idea of where exactly to look for the open circuit fault between T6/3 and earth. Have not yet tested the other 5 devices to earth, but as you have also mentioned if other devices were not earthed then they would give DTC’s . They do not, so more inclined to focus on the EGR T6/3 earth.

Not certain if the common earth on “85” is daisy chained or if all 6 device earths go directly to “85 earth connection 1 in engine compartment wiring harness”

Currently have no idea where “85 earth connection 1 in engine compartment wiring harness” is. Any ideas of physically where this is or where to look for our fault appreciated!