T6 cutting stereo and power cutting out under acceleration

HighTop

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VIP Member
Hi all,

Been having an expensive nightmare trying to get to the bottom of this gremlin. I have checked all of the other threads related to power loss and can't find a similar set of symptoms.
When accelerating, the vans stereo will occasionally flick off briefly, displaying the 'dont forget your mobile phone' message. If this is a quick flicker there is no further problem but if it lasts longer, the van will stop accelerating. It has never stalled, but the loss of power is enough to cause a mild heart attack on slip roads etc. If the power loss is longer, then the coil lights come on and the van goes into limp mode until I restart. If it's a brief power loss then no codes are stored. When it's the longer power loss, it gave codes P060c00 and P20ee00. These flagged up a software update fix. Tried this as first step but not helped.
Replaced the earth strap to rule out corrosion. My local independants diagnosed faulty ignition starter switch. This was changed with no difference. Finally I asked them to unplug battery monitoring control unit and test. They thought this had worked and I took the van home today. Unfortunately on a short drive the stereo has started going again although not yet long enough to cause the lack of power.
Has anyone had any similar issues? I'm guessing it's a shorted damaged cable somewhere.
As an aside if it's playing up then regens on a long drive it will be fine after this, until I turn it off and on again. Thank you for any advice
 
I would start by doing a scan for any fault codes, but it does sound like a fault with the ignition wiring or switch.

From what I have read on the forum (altough not showing the issue you have) ignition switches seem to fail occasionally
 
Thanks, ignition switch replaced and that didn't fix the issue so I think there is going to be an issue with the wiring somewhere. Latest faults from last night...

CAN network gateway:
00470 - Comfort CAN-bus in 1-wire mode: Electrical error in circuit
Freeze frame
Priority: 2
Malfunction frequency counter: 54
Unlearning counter: 221
Odometer reading: 191816 km

01336 - Comfort CAN bus: No signal/communication
Freeze frame
Priority: 2
Malfunction frequency counter: 6
Unlearning counter: 5
Odometer reading: 191816 km

Instrument cluster:
U112100 - Databus missing message
Freeze frame
Priority: 6
Malfunction frequency counter: 2
Unlearning counter: 6
Odometer reading: 191845 km

Infotainment system:
U112100 - Databus missing message
Freeze frame
Priority: 6
Malfunction frequency counter: 7
Unlearning counter: 6
Odometer reading: 191816 km

U112100 - Databus missing message
Freeze frame
Priority: 6
Malfunction frequency counter: 8
Unlearning counter: 6
Odometer reading: 191816 km

U112100 - Databus missing message
Freeze frame
Priority: 6
Malfunction frequency counter: 8
Unlearning counter: 6
Odometer reading: 191816 km

U112100 - Databus missing message
Freeze frame
Priority: 6
Malfunction frequency counter: 8
Unlearning counter: 6
Odometer reading: 191816 km

U112100 - Databus missing message
Freeze frame
Priority: 6
Malfunction frequency counter: 7
Unlearning counter: 6
Odometer reading: 191816 km

U112100 - Databus missing message
Freeze frame
Priority: 6
Malfunction frequency counter: 7
Unlearning counter: 6
Odometer reading: 191816 km

U112100 - Databus missing message
Freeze frame
Priority: 6
Malfunction frequency counter: 7
Unlearning counter: 6
Odometer reading: 191816 km

U112100 - Databus missing message
Freeze frame
Priority: 6
Malfunction frequency counter: 7
Unlearning counter: 6
Odometer reading: 191816 km

U120100 - Data bus: no communication
Freeze frame
Priority: 2
Malfunction frequency counter: 7
Unlearning counter: 6
Odometer reading: 191816 km

Battery regulator:
00458 - Battery Monitoring Control Module: No signal/communication
Freeze frame
Priority: 2
Malfunction frequency counter: 2
Unlearning counter: 219
Odometer reading: 191816 km

Trailer:
00457 - Vehicle Electrical System Control Module: No signal/communication
Freeze frame
Priority: 6
Malfunction frequency counter: 4
Unlearning counter: 6

01299 - Data Bus On Board Diagnostic Interface: No signal/communication
Freeze frame
Priority: 6
Malfunction frequency counter: 9
Unlearning counter: 6
Odometer reading: 191816 km

01336 - Comfort CAN bus: No signal/communication
Freeze frame
Priority: 1
Malfunction frequency counter: 8
Unlearning counter: 6
Odometer reading: 191816 km

Obtained with Carista 9.3.1 for Android.
Download app: Carista OBD2 - Apps on Google Play
Facebook: Carista
 
Just to note with above scan, the battery monitor is currently unplugged to see if that prevented the issue.
 
I guess would be more than helpful to know what's the vehicle in question. Please post "Detailed ECU info"-report (under Carista Service menu).

So what happened at "Odometer reading: 191816 km"?
 
Thanks for the guidance, will post the detailed info when back from work this afternoon. For now, it's a 2017 150 T6 CXHA 4motion. Not sure if the odometer reading is when codes were last reset?
 
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I guess would be more than helpful to know what's the vehicle in question. Please post "Detailed ECU info"-report (under Carista Service menu).

So what happened at "Odometer reading: 191816 km"?
Detailed ECU info pasted below... I can only assume that at 191816km was the first instance of everything going wrong after the last code reset.
The battery module is still unplugged, hence the fault. Not sure why there's so many trailer faults. It does have a towbar fitted although I have never used it. Also wondering if the ctek b2b charger could be causing trouble with the voltage, so will disconnect that next.

ECU info obtained with Carista 9.3.1 for Android:

VIN:

CAN network gateway
Part #: 7E0909901
Component: GW-K-CAN TP20
Software version: 0744
ASAM/ODX identifier: [none]
Coding: 042305 (hex)
Fault codes:
00470 Comfort CAN-bus in 1-wire mode: Electrical error in circuit
01336 Comfort CAN bus: No signal/communication

Engine
Part #: 04L906056KJ
Component: R4 2.0l TDI
Software version: 6167
ASAM/ODX identifier: EV_ECM20TDI03004L906056KJ
Coding: 00194010431701090000 (hex)
[No fault codes]

ABS
Part #: 7E0907379P
Component: ESC
Software version: 0133
ASAM/ODX identifier: EV_Brake1ESCCONTIVN75XGP2
Coding: 867E8098256A8483617E0178A48221A6790000 (hex)
[No fault codes]

Steering angle
Part #: 6R0959654
Component: LENKW.SENSOR
Software version: 0070
ASAM/ODX identifier: EV_LWSKLOVW25X
Coding: 01 (hex)
[No fault codes]

Airbags
Part #: 7E0959655G
Component: VW10Airbag021
Software version: 0018
ASAM/ODX identifier: EV_AirbaVW10BPAVW12X
Coding: 000000000000000000000000000000003231 (hex)
[No fault codes]

Instrument cluster
Part #: 7E0920960S
Component: KOMBI
Software version: 1104
ASAM/ODX identifier: EV_Kombi_UDS_VDD_RM09
Coding: 450B010300 (hex)
Fault codes:
U112100 Databus missing message

Infotainment system
Part #: 1K8035150L
Component: MU-E-D-ER
Software version: 7085
ASAM/ODX identifier: EV_MUEnt4CGen2LGE
Coding: 065700003C00000041111101008000001F0000C60000010001 (hex)
Fault codes:
U112100 Databus missing message
U112100 Databus missing message
U112100 Databus missing message
U112100 Databus missing message
U112100 Databus missing message
U112100 Databus missing message
U112100 Databus missing message
U112100 Databus missing message
U120100 Data bus: no communication

Immobilizer
Part #: 5K0953234
Component: IMMO
Software version: 1104
ASAM/ODX identifier: EV_Immo_UDS_VDD_RM09
Coding: 000000 (hex)
[No fault codes]

All-wheel-drive system
Part #: 0AY907554L
Component: Haldex4Motion
Software version: 7620
ASAM/ODX identifier: EV_AllWheelContrHA1VW37X
Coding: 0501 (hex)
[No fault codes]

Central electronics
Part #: 7E0937090B
Component: BCM PQ25 Max4
Software version: 0744
ASAM/ODX identifier: [none]
Coding: E0A4303A0A212031002009742C2B8C500F00708F60464D60320400220800 (hex)
[No fault codes]

Battery regulator
Part #: 7E0907534
Component: Batt.regelung
Software version: 0744
ASAM/ODX identifier: [none]
Coding: 330B7A73 (hex)
Fault codes:
00458 Battery Monitoring Control Module: No signal/communication

Trailer
Part #: 1K0907383H
Component: Anhaenger
Software version: 0130
ASAM/ODX identifier: [none]
Coding: 410D000103000000 (hex)
Fault codes:
00457 Vehicle Electrical System Control Module: No signal/communication
01299 Data Bus On Board Diagnostic Interface: No signal/communication
01336 Comfort CAN bus: No signal/communication
 
IMG_20250801_151128.webpJust checked in fuse box and there were quite a few piggyback fuses, some of which had come out of the holders a little bit. Will test and make sure all are secure. Should have started here weeks ago...
 
So fuses checked, battery monitor plugged back in, faults cleared for a test. Stereo cut out before I left the drive! Will stop spamming loads of posts for a while!
 
00470 Comfort CAN-bus in 1-wire mode: Electrical error in circuit.
Google that.

That's the issue apparently. It's gone from 2 wire mode to 1 wire mode.
Problem is there's a lot of wiring to check that goes back to the CAN so it's not much help other than to suggest there is a short or break in the wiring somewhere on the van.
Done any other work on the van recently prior to the issue like maybe screwing something into the van that may have hit a wire?
 
Last edited:
00470 Comfort CAN-bus in 1-wire mode: Electrical error in circuit.
Google that.

That's the issue apparently. It's gone from 2 wire mode to 1 wire mode.
Problem is there's a lot of wiring to check that goes back to the CAN so it's not much help other than to suggest there is a short or break in the wiring somewhere on the van.
Done any other work on the van recently prior to the issue like maybe screwing something into the van that may have hit a wire?
Thanks, there's no work been carried out recently. The technician at the local garage said most T6s he works on are in single wire mode so he didn't see that as an issue. If that's the likeliest cause then I guess I know what my weekend plans are!
 
Not sure why there's so many trailer faults.
00470 Comfort CAN-bus in 1-wire mode: Electrical error in circuit
01336 Comfort CAN bus: No signal/communication
Trailer controller is on Comfort CANbus.

there were quite a few piggyback fuses,
I'm afraid some of them are wrong way thus not correctly fused. I think they should "exit" to the left.
How about disconnecting those extra circuits to simplify fault finding?

P060C 00 - Internal Control Module - Main Processor Performance
Engine
Part #: 04L906056KJ
Component: R4 2.0l TDI
Software version: 6167
Interestingly there is a very recent update for this engine - that's quite unusual - perhaps worth to get that one to eliminate software issue with engine cutting off?
1754080773617.webp
 
Thanks for all the tips. Will start with the fuses and see if I can trace the fault. Unfortunately, I couldn't convince the vw van centre to give me a free upgrade. They wanted £170 for the last one. They did offer to put a claim in with VW for getting the money back with no guarantees. As I wasn't sure if the software was the issue, I paid my local independant garage a lot less to do this and then continue the fault finding.
 
Just as an update, been on a 30min drive just now, and every time I slowed down I could see the head unit dimming before it displayed the 'do not forget your mobile phone message'. Short power loss was no problem, but longer caused the van to stop accelerating again. Just wondering if this is pointing to anything specific before I delve into the wire tracing!
 
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So one more update... Unplugged the OEM stereo (that was absolutely red hot, almost untouchable) and went for a test drive. Absolutely no problems with power loss experienced 😊. Could a stereo gremlin have fed a fault back down the wiring to the ignition? A quick forum search hasn't shown anything apart from the overheating CD player issues.
 
So with the van running fine for a couple of weeks although with no stereo I asked @Absolut5 for a quote for a new head unit, speakers etc. He kindly advised me that an aftermarket stereo would not work if the can bus was in single wire mode and he has seen stretched wires under seats from conversion companies leading to problems. As the van came with a double swivel seat when we bought it, I unbolted it to take a look. As can be seen from the pic there is a lot of damage where the swivel seat has rubbed on the wires. Shouldn't these seats be fitted with a protective plate at least? I will start going through the separate units to see if any wires have rubbed through under the tape. Please could anyone advise which is the trailer wiring plug? As this is an easy one to rule out as its a consistent fault in carista. ThanksIMG_20250816_103953.webp
 
On my van the ecu for the trailer is under the drivers seat, not the double passenger seat. I'm not sure where the wiring for that goes, but would probably be easy enough to trace to see if it goes across to the passenger side.
 
The issue we experienced was under the drivers seat, had safe seat vases fitted and for some reason they stressed the wiring/plugs by using cable ties to pull the cable tight, no reason for doing it as they were all in the plastic holder
 
Thank you to all for your advice and help. I took the van to @Dav-Tec yesterday and he had me up and running with a working stereo within 2 hours! As @Absolut5 had mentioned, the wires under the drivers seat were damaged. It looks like they had been damaged when a diesel heater had been fitted. Both the canbus wire and a 12v power cable had been partially snipped. Over time they had corroded and the 12v power was being arcing repeatedly into the can bus wire, causing the power loss and stereo shut down. Perfect resolution in the end and I ended up forking out for a single captain swivel seat from vw-bidesign next door!
IMG-20250826-WA0027.jpg
 
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