2016 Passat Electrical Firestorm

[Polska111]

Hey guys!

Got a 2016 Passat Alltrack with demons.

About 2 weeks ago my car started throwing every electrical system error under the sun. It would do it on ignition power, and only do it 1 in every 30-50 starts.

Each time it happened, Id turn the ignition off, attempt to restart the car and it'd start, run and drive no problem.

It was previously only doing this at ignition at startup, however today it did it mid drive and switched off in the middle of a highway.

Ive got a few small elec issues Im aware of (front air distribution servo, windshield washer pump motor), but this is a mess, and no shop is available to diagnose it for nearly a month.

Some errors I keep seeing in my logs are "Databus message missing/implausible/error value received" (across all literally every control unit), and "Lost Communication with ECM/PCM", which suggests to me either canbus or ECU?

Any ideas?

You can see the full error log at:

Dropbox (https://www.dropbox.com/scl/fi/56scgpjzt3ckca00a4g5k/Passat-Error-Log-OBD11-2025-01-22.txt?rlkey=29ayrlvt8dg6hc8813mxe5yqk&e=1&dl=0&mweb=1)

TIA!562765627756278562795628056281http://cloud.tapatalk.com/s/678f752e4d1d2/OBD11%20Log.pdf

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[BeigeJet]

Have you tried any local independent VW specialists in your area.

If not may be worth a try at Volkscare in Bayswater. Boris is the owners name.

They've been very helpful in the past with our 2006 Jetta TDI

[Polska111]

Have you tried any local independent VW specialists in your area.

If not may be worth a try at Volkscare in Bayswater. Boris is the owners name.

They've been very helpful in the past with our 2006 Jetta TDII usually take it to Peninsula Autohaus in Frankston but earliest they can do is early Feb, but Im gonna dona whip around tomorrow and see if anyone can book me in sooner.

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[hulbyw]

Volkscare or Volkwerke in Doncaster. Both good shops

[DV52]

@Polska111. Hi.

Hmm....... obviously from your pictures, there are multiple-problems with this car! If we could actually see the content of your OBD11 scan - stuff would be much clearer!!

Maybe first add Freeze-frame to your OBD11 account (read THIS (https://support.obdeleven.com/en/articles/5608816-what-is-freeze-frame-data)) - then make a fresh SCAN and post-up (make sure that it actually works)

Don

[Gutoneto]

Hey guys!

Got a 2016 Passat Alltrack with demons.

About 2 weeks ago my car started throwing every electrical system error under the sun. It would do it on ignition power, and only do it 1 in every 30-50 starts.

Each time it happened, Id turn the ignition off, attempt to restart the car and it'd start, run and drive no problem.

It was previously only doing this at ignition at startup, however today it did it mid drive and switched off in the middle of a highway.

Ive got a few small elec issues Im aware of (front air distribution servo, windshield washer pump motor), but this is a mess, and no shop is available to diagnose it for nearly a month.

Some errors I keep seeing in my logs are "Databus message missing/implausible/error value received" (across all literally every control unit), and "Lost Communication with ECM/PCM", which suggests to me either canbus or ECU?

Any ideas?

Ive uploaded the full log as a .PDF.

TIA!562765627756278562795628056281http://cloud.tapatalk.com/s/678f752e4d1d2/OBD11%20Log.pdf

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The log link it's not working. Could you please post here?

I think your problem is related to the gearbox. All those system relies on signals from the TCU to work. When my TCU was dying I had all those random errors on the MFD as well, but won't be able confirm until see the logs.

Is your Alltrack 6 or 7 speed?

[Polska111]

Hey guys, thanks foe the replies!

Ive uploaded the log as a txt doc here:

Dropbox (https://www.dropbox.com/scl/fi/56scgpjzt3ckca00a4g5k/Passat-Error-Log-OBD11-2025-01-22.txt?rlkey=29ayrlvt8dg6hc8813mxe5yqk&dl=0)


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[Polska111]

@Polska111. Hi.

Hmm....... obviously from your pictures, there are multiple-problems with this car! If we could actually see the content of your OBD11 scan - stuff would be much clearer!!

Maybe first add Freeze-frame to your OBD11 account (read THIS (https://support.obdeleven.com/en/articles/5608816-what-is-freeze-frame-data)) - then make a fresh SCAN and post-up (make sure that it actually works)

Don

Hey Don, Ive uploaded the txt log here:

Dropbox (https://www.dropbox.com/scl/fi/56scgpjzt3ckca00a4g5k/Passat-Error-Log-OBD11-2025-01-22.txt?rlkey=29ayrlvt8dg6hc8813mxe5yqk&dl=0)

Thanks for the reply!


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[Gutoneto]

You have two lost of communication with the TCU and I would start with that. As mentioned, that can cause an avalanche of erros on all the other modules/systems.


U010000 - Lost Communication with ECM/PCM

Intermittent

U010000 - Lost Communication with ECM/PCM

Intermittent



Have you checked if you have any oil coming out of the mechatronic connector?

[Polska111]

You have two lost of communication with the TCU and I would start with that. As mentioned, that can cause an avalanche of erros on all the other modules/systems.


U010000 - Lost Communication with ECM/PCM

Intermittent

U010000 - Lost Communication with ECM/PCM

Intermittent



Have you checked if you have any oil coming out of the mechatronic connector?

I dropped the car in this morning so Im unable to check, but I haven’t noticed any oil spots on the drive nor under the vehicle.

Where would I find the TCU and connector? I cant seem to find much on location online.


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[Guest001]

Failing battery can cause light shows like that

[Polska111]

Failing battery can cause light shows like that

My thought too, but got battery tested and was all ok.


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[Guest001]

My thought too, but got battery tested and was all ok.


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Had similar wouldnt hurt to try another one to see Fixed mine and it tested fairly OK

[DV52]

@Gutoneto: Hi again - are you settled-in yet? Hope everything is OK in your new abode!

Hmm........ no offense and maybe I'm reading a different SCAN, but I suspect that your interpretation of the U010000 errors is a tad erroneous. Yes, the 2 x error messages have been recorded in the 02 module - but again with no offense intended, the story they tell me is that the culprit here is perhaps the 01 module (not the TCU).

My reading of these errors is supported by the fact that the Gateway module has also recorded the same U010000 error.
So, my hunch is that this problem may have its genesis in the 01 module's ability to remain in continuous communication with the central CAN spine on this car - I think!

The "usual" reason for module comms failures is either a problem with the CAN high/low wires (open/short circuit), or a power supply problem. The intermittent status of the errors on this car suggests that perhaps a multi-meter and a wiring diagram might be useful as a prelude to focused diagnostic testing (dependent on OP's answer to my question below).

@Polska111: Please confirm that the Engine Control Unit (ECU) on this car is factory original and that there have been absolutely NO (meaning "none") coding changes to this car.

Alas, there is NO Freeze-frame data in your SCAN as I requested. Clearly you have chosen to post-up yesterday's SCAN - which is entirely your prerogative, of course! The missing data greatly restricts how the story-line in your SCAN can be read -so I can't comment except to reiterate that it would help to have Freeze-frame data (especially given the multitude of errors on this car)!!

Anyhow -do the following (if you want):


Enable Freeze-frame as I requested and make a fresh SCAN.
Then clear ALL errors and cycle the ignition (without the engine running) - do the errors re-appear?
Then start the engine - do the errors re-appear?


Don

[Polska111]

@Gutoneto: Hi again - are you settled-in yet? Hope everything is OK in your new abode!

Hmm........ no offense and maybe I'm reading a different SCAN, but I suspect that your interpretation of the U010000 errors is a tad erroneous. Yes, the 2 x error messages have been recorded in the 02 module - but again with no offense intended, the story they tell me is that the culprit here is perhaps the 01 module (not the TCU).

My reading of these errors is supported by the fact that the Gateway module has also recorded the same U010000 error.
So, my hunch is that this problem may have its genesis in the 01 module's ability to remain in continuous communication with the central CAN spine on this car - I think!

The "usual" reason for module comms failures is either a problem with the CAN high/low wires (open/short circuit), or a power supply problem. The intermittent status of the errors on this car suggests that perhaps a multi-meter and a wiring diagram might be useful as a prelude to focused diagnostic testing (dependent on OP's answer to my question below).

@Polska111: Please confirm that the Engine Control Unit (ECU) on this car is factory original and that there have been absolutely NO (meaning "none") coding changes to this car.

Alas, there is NO Freeze-frame data in your SCAN as I requested. Clearly you have chosen to post-up yesterday's SCAN - which is entirely your prerogative, of course! The missing data greatly restricts how the story-line in your SCAN can be read -so I can't comment except to reiterate that it would help to have Freeze-frame data (especially given the multitude of errors on this car)!!

Anyhow -do the following (if you want):


Enable Freeze-frame as I requested and make a fresh SCAN.
Then clear ALL errors and cycle the ignition (without the engine running) - do the errors re-appear?
Then start the engine - do the errors re-appear?


Don

As the vehicle is currently at the shop I cannot conduct a scan, however, the ECU is original, and has 1 minor coding change which was to enable paddles (as I had a steering wheel swap).

Forgive my newbieness,but what is the 01 Module, the ECM/ECU?

Now that think of it, this issue did first arise after I did a “disable safety disclaimer” code change (via an obd11 app) which I have since reversed. I could not imagine how this could have been the cause however being such a basic on/off code change.

I did not have the vehicle to re-scan with freeze frame, however if they are unable to diagnose the issue or if they are unable to do it within a reasonable time I will go back and re-scan with FF enabled. I was unaware this was a feature until I had posted in here, so thank you to all who have recommended enabling it!


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[DV52]

Forgive my newbieness,but what is the 01 Module, the ECM/ECU?

No need to seek forgiveness - we were ALL new-bees at some stage in our learning journey in the dark arts of diagnostic devices like OBD11!!

There are a gazillion different TLAs (Three-Letter Acronyms) used in the language of vehicle technology - so its not unlike every other field of endeavor in the modern age!! The TLAs below might help in your understanding of these responses



TCM = Transmission control module
ECM = Engine Control Module
ECU = Engine Control Unit
PCM = Powertrain Control Module


So, ECM and ECU have ostensibly the same meaning. TCM is sometimes called the "Mechatronic Unit/Module" on dual clutch gearboxes. PCM is mentioned in the U010000 error (Lost Communication with ECM/PCM). I suspect "Powertrain" when used in the context of the error message refers to the combination of ECM and TCM. However, on a MQB platform car like this Passat, separate modules are used to control the engine and the transmission - and the term "Powertrain" has a particular meaning; it relates to the "Powertrain CAN bus" which looks like this:

https://www.vwwatercooled.com.au/forums/images/imported/2025/01/luawk5Hpng-1.jpg



Now that think of it, this issue did first arise after I did a “disable safety disclaimer” code change (via an obd11 app) which I have since reversed. I could not imagine how this could have been the cause however being such a basic on/off code change.

Hmm.......... OK, you are clearly a "One-Click-App" user then - that's not good! I NEVER use OCA's because they make changes to the car's coding that are NOT disclosed. This is not a problem if the OCA works - but when the loose stools in the moist brown stuff collide with the proverbial fan blades, these secret coding changes can be a disaster to unwind. If you doubt that OCAs do not sometimes work - look on the OBD11 forum for many examples!

So, my suggestion is that you view OCAs like throwing dice (they are a gamble with REAL consequential risks); lots of times you win - but some times you lose! And the more OCAs that you use - the greater will be the risk of disaster!!

Again, I NEVER use OCA's and I urge that you consider making ALL coding changes with OBD11 manually!

Don

[Polska111]

No need for apology - we were ALL new-bees at some stage in our diagnostic device learning journey!!

There are a gazillion different TLAs (Three-Letter Acronyms) used in the language of vehicle technology - so its not unlike every other field of endeavor in the modern age!! The TLAs below might help in your understanding of these responses



TCM = Transmission control module
ECM = Engine Control Module
ECU = Engine Control Unit
PCM = Powertrain Control Module


So, ECM and ECU have ostensibly the same meaning. TCM is sometimes called the "Mechatronic Unit/Module" on dual clutch gearboxes. PCM is mentioned in the U010000 error (Lost Communication with ECM/PCM). I suspect "Powertrain" when used in the context of the error message refers to the combination of ECM and TCM. However, on a MQB platform car like this Passat, separate modules are used to control the engine and the transmission - and the term "Powertrain" has a particular meaning; it relates to the "Powertrain CAN bus" which looks like this:

https://www.vwwatercooled.com.au/forums/images/imported/2025/01/luawk5Hpng-1.jpg



Hmm.......... OK, you are clearly a "One-Click-App" user then - that's not good! I NEVER use OCA's because they make changes to the car's coding that are NOT disclosed. This is not a problem if the OCA works - but when the loose stools in the moist brown stuff collide with the proverbial fan blades, these secret coding changes can be a disaster to unwind. If you doubt that OCAs do not sometimes work - look on the OBD11 forum for many examples!

So, my suggestion is that you view OCAs like throwing dice (they are a gamble with REAL consequential risks); lots of times you win - but some times you lose! Again, I NEVER use OCA's and I urge that you make ALL coding changes with OBD11 manually!

Don

Thank you for the breakdown!

Yes I have used OCAs before mainly out of convenience.

Is there any way to view what the processes within the OCA is so that you can reverse engineer/wind back what was done by it, without relying on the OCA itself to just reverse the state back?

Alternatively, is there a way to do an ecu factory reset, or preferably, reverse it back to what it would have been at the time exiting the factory?

Im not sure if there is a repository for default module settings based on VIN.

Wishful thinking perhaps.


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[DV52]

Is there any way to view what the processes within the OCA is so that you can reverse engineer/wind back what was done by it, without relying on the OCA itself to just reverse the state back?

As I said in my previous reply "OCA's .........make changes to the car's coding that are NOT disclosed". So the answer to your specific question about OCAs is a resounding NO!

However, this ain't the case if you make coding changes manually. To understand the difference with manual coding - you first need to understand what happens inside the car's module when you make coding changes. Regardless of whether you use OCAs, or manual coding - the change process inside the module is that the new-value is written over the old -value and the old-value is lost!

However, good diagnostic devices (like OBD11) use separate software to "catch" the old-value before it is lost by the module -but this happens for code changes ONLY if they are done manually. OBD11 saves a detailed record of every manual process that you undertake with the device. This includes stuff like SCANs, manual coding changes (to both adaptation channels and long-code strings), Basic settings, Backups, Faults and lots, lots more. But NOT OCAs!

The database is stored against your OBD11 account and it can be accessed anytime without connecting to the dongle by selecting History. I suggest that you look on your OBD11 account for the History database (if you use the iOS version software, Select Garage on the Home screen)




Alternatively, is there a way to do an ecu factory reset, or preferably, reverse it back to what it would have been at the time exiting the factory?

I'm not sure if there is a repository for default module settings based on VIN.

Wishful thinking perhaps.

Yes, this car does indeed have a default "repository" and yes it is VIN based! ALL MQB platform cars that roll-off the factory production line have a complete copy of each module's factory programming stored (by VIN) on the central servers on the VAG mother-ship. This database is called FAZIT - which is the German acronym for "Vehicle information and central identification tool".

To access the database, a remote connection is required to FAZIT - but this is a restricted facility that's only available to dealers and other authorized agents that have registered GeKo accounts. This is a fee-for-service facility that's completely outside the reach of any third party diagnostic device like OBD11!