Hi all,

Wondering if someone has experienced similar or can point to what may be the root cause. About a month a go, the EPC light came on and I started losing power, couldn’t rev above 10k then error after error started flashing up (Auto Start stop, tail light, brake light, every kind of light you can think of). Parked up, switched car off then tried switching back on it wouldn’t switch on. Long story short, recovery came, ran diagnostics and mentioned all errors including one about Fuel Rail/System Pressure low. However, by this time, after being off for about an hour, the car started fine. So recovery person cleared all errors, revved and ran some tests and said all looks fine, could’ve been a temp fault. Drove off no issues until last night. Same thing again but this time car wouldn’t start even after an hour. Recovery came again, same errors is diagnostics, battery was checked and all good on that side. Have dropped off to garage but hoping it’s nothing major (ECU issues? Fuel pump?). Below is the diagnostic output:

ENGINE SYSTEM TEST/VALUES

• Name:CJZD - MOTRONIC TSI

• DTC:U112300,CAN communication; fault/defect

• DTC:U021200,No communication steering wheel electronic

• DTC:U015500,Instrument control unit communication fault

• DTC:U014600,No communication gateway

• DTC:P008700,Fuel Rail/System Pressure - Too Low

BRAKES

• Name:ABS/ESP - DIAGNOSE

• DTC:U112100,CAN-Bus Failure - No CAN-Message

• DTC:C10A301,Underpressure sensor; electrical fault

WHEEL SYSTEM

• Name:TIRE PRESSURE MONITORING SYSTEM

• DTC:U112100,CAN-Bus Failure - No CAN-Message

• DTC:C10A301,Underpressure sensor; electrical fault

INSTRUMENT PANEL

• Name:INSTRUMENT - DIAGNOSE

• DTC:U112100,CAN-Bus Failure - No CAN-Message

DRIVER ASSISTANCE SYSTEM

• Name:DISTANCE CONTROLLER - DIAGNOSE

• DTC:U112100,CAN-Bus Failure - No CAN-Message

• DTC:B200FF0,Internal malfunction

CJZD - MOTRONIC TSI

• Name:CJZD - MOTRONIC TSI

• DTC:U112300,CAN communication; fault/defect

• DTC:U021200,No communication steering wheel electronic

• DTC:U015500,Instrument control unit communication fault

• DTC:U014600,No communication gateway

• DTC:P008700,Fuel Rail/System Pressure - Too Low

ABS/ESP - DIAGNOSE

• Name:ABS/ESP - DIAGNOSE

• DTC:U112100,CAN-Bus Failure - No CAN-Message

• DTC:C10A301,Underpressure sensor; electrical fault

CLIMATE CONTROL

• Name:CLIMATE CONTROL

• DTC:B10F000,Function limitation due to Compressor Shut-Off by engine

CENTRAL ELECTRONICS - DIAGNOSE

• Name:CENTRAL ELECTRONICS - DIAGNOSE

• DTC:B11EB15,Right rear turn signal bulb

• DTC:B12BF15,Right tail lamp bulb

• DTC:B12BF01,Right tail lamp bulb

• DTC:B12C815,Right rear fog light bulb

• DTC:B12CD01,Back-up lamp

• DTC:B133C15,Right brake/tail lamp bulb

• DTC:B116229,Selector lever park position lock switch

DISTANCE CONTROLLER - DIAGNOSE

• Name:DISTANCE CONTROLLER - DIAGNOSE

• DTC:U112100,CAN-Bus Failure - No CAN-Message

• DTC:B200FF0,Internal malfunction

INSTRUMENT - DIAGNOSE

• Name:INSTRUMENT - DIAGNOSE

• DTC:U112100,CAN-Bus Failure - No CAN-Message

STEERING ASSISTANCE - DIAGNOSE

• Name:STEERING ASSISTANCE - DIAGNOSE

• DTC:104F00,unknown

INFOTAINMENT - INFORMATION ELECTRONICS 1

• Name:INFOTAINMENT - INFORMATION ELECTRONICS 1

• DTC:B127313,Connection between antenna amplifier 2 and antenna

• DTC:B110311,Digital radio antenna 1

Hi, welcome.

So many things to check that might throw this up, proper diagnostics required, and being intermittent is a PITA so you might have to throw in wiggle, hot, cold, water/damp tests. Certainly start at the battery and main power and earth connections and leads, then you might test fuses, relays, ignition/start buttons, modules, wires, connections, etc.. Then the computer systems are complex and intertwined so if there is a second or more contributing problems it could be back loading from lots of sources. The CAN bus can be off from the starting point and/or or points playing it up.

You've not put which (part)year your car is or if it's DSG and or KESSY (light or to me full nuisance), IIRC the CJZD is the 1.2 TSI with extra turbo(?).

Intermittent or not for electrical stuff on a car I don't know I'd (not that I know or can do much) always start at the very basics, that are often missed by even the knowledgeable and experienced, from battery posts on, are the terminal posts clean, and terminal post clamps clean (inside and out) and securely fitted, then main battery leads and their connections, check battery state of charge and condition - then plug in the scan tool to see what it has.

Let us know how you get on if you're lucky you might get someone good at diagnostics and find it's something quite straightforward and easy fix despite it looking so dramatic.

See this chap who gets similar with other cars/vans and how he solves them. - https://www.youtube.com/@mrautoservices7354

There are loads of ECUs in a modern car - and to reduce wiring, they communicate with each other using a data circuit called the CAN bus. i.e. they are actually messaging each other. I'm looking at all those errors and the common thread is CAN bus issues all over the place - so I think it's probably the CAN bus wiring itself (intermittent break, short etc.).

If you consider the CAN bus as the car equivalent of a your spinal cord, you can begin to understand what sort of chaos a fault on it is going to cause - and I think that is exactly what you are seeing. It could be a simple wiring fix, but finding the fault might take the garage a bit of time.

i had similar problems. which was a bad battery and a lose cable to my tubo. the dealer fixed the cable thing i and installed 90 ah battery and everything worked here.

Good point that there could be more than one issue contributing to the problem and as the systems are so complex and intertwined a seemingly unrelated issue could contribute or cause the problem.

A 90(?)Ah battery could be useful in a very cold or very hot location but would be very large for general UK use, unless the electric loads or use are a lot more than generally here.

It sounds like the CAN system is not functioning at all. One thing that can go wrong is a fault on another controller (ECU) on the system or an item linked to a controller which can cause the CAN system to go down by broadcasting garbage. It's interesting that you have so many right rear bulb codes. I think I would remove the right lamp holder to take it out of the equation. You may come across some corrosion or dampness there.

If you can get access to VCDS you can see the status of the CAN connection for each controller (engine, air bags, ABS etc). Assuming you have enough communication at the time to make diagnostics possible which doesn't look very hopeful!

I've had a dig about and found a good guide on YouTube to CAN bus faults which I thought was worth sharing. The OP stated that the battery had already been checked but I noticed that the first recommendation on this video was to do just that, so it's clear there can be a link as some of you have said.

@Rheumy Agreed, problem is it is difficult to know what is and isn't related in this case. All the rear lighting is off the body control module so I can't see why there would be a connection to any CAN bus issue with those errors. So maybe an intermittent bad earth - perhaps another issue of wire breakages in the tailgate grommet? I happened to spot another familiar error code in there - the B116229 gear selector one and I bet I know what that is 😄

Thanks for all the replies, car is still at the garage, unfortunately they could not look at it on Friday and were closed on weekend. Will post an update once diagnosed. One thing to re-emphasise, the first thing that happened on both occasions was the EPC light coming on, losing power and not being able to rev beyond 10k and then all warnings about lights coming on. Still hoping it's something small.

Safety always comes first in the order of things so if any critical system develops a fault it will limit performance to persuade you to stop asap. Many other systems will come out in sympathy (and warning lights and codes) when they also don't get the constant messages they expect from their neighbours. It could be something as simple as a fuse or more involved like a break in the wiring or faulty controller. Good luck and fingers crossed for you!

@Yorkshiremidge's video link is a good description of how interconnected these systems are on modern cars even if you don't particularly understand the testing procedures. Personally I'm glad I retired years ago!

With so many lack of communication error codes I'd not take too much notice of any of the other error codes until more diagnostics and information is done and available.

I put a link to a good diagnostics chap for general information and examples of how things are so intertwined, his latest video is a good example, knowledge, experience and access to the right information also helps but like everyone he had to learn things for a first time to know them now. BTW nothing wrong with suitable good quality LED bulbs but many buy cheap crap that can cause issues. - https://www.youtube.com/watch?v=js4XbiFl2Yc

Quick update: car is back with me and so far so good. The garage could not pinpoint the issue as they did not have an electrical expert, fortunately managed to find a good mechanic after a lot of searching online. Main issue was oxidation in some of the connectors leading to increased resistance. A secondary issue (which may not have caused this issue but needed resolving) was battery charging at a lower voltage than it should due to battery adaptation not being updated when battery was changed.

Thanks for reporting back.

12 hours ago, Falaq said:

A secondary issue (which may not have caused this issue but needed resolving) was battery charging at a lower voltage than it should due to battery adaptation not being updated when battery was changed.

Battery state of charge is very important to these cars. Sod's Law, I often start with battery state of charge on many issues but not this time - battery was mentioned and by others but not state of charge and recharging this time, that's Sod's Law.

The headlights may seem bright enough and the engine starts easily but the 12v battery state of charge may be too low for the computers and they often throw up all sorts of unexpected warnings and lights, issues - and unseen error codes. There are lots of threads and posts on here and other sites about this on all models.

Get the battery corrected 'coded', there is lots of info for this on this site or just ask even before it is 'coded' check the state of charge on your battery and if necessary recharge it using a suitable battery charger maintainer following the instructions for doing so in the car's 'Owner's Manual' and for the charger maintainer, recharge the battery to full (or at least 80%) on the charger.

The battery may have been weakened by the incorrect charging so do check its state of charge regularly for a while to check it can be charged well.

Even a good battery is best to do very occasional when required preventative (not at or after it is low) recharging using a suitable battery charger maintainer following the instructions for doing so in the car's 'Owner's Manual' and for the charger maintainer, recharge the battery to full (or at least 80%) on the charger to have a long and reliable useful battery life.

VWŠkoda 'Owner's Manual' site. - https://www.skoda-auto.com/apps/manuals/Models

Do not underestimate the importance of the 12v battery (and charging) on modern cars and how much the computer systems are effected, the 12v battery has always been very important but much more so now (even on electric cars) because of the computer systems as well as the other electrics.

12 hours ago, Falaq said:

Quick update: car is back with me and so far so good. The garage could not pinpoint the issue as they did not have an electrical expert, fortunately managed to find a good mechanic after a lot of searching online. Main issue was oxidation in some of the connectors leading to increased resistance. A secondary issue (which may not have caused this issue but needed resolving) was battery charging at a lower voltage than it should due to battery adaptation not being updated when battery was changed.

This is the sort of fault where you're into auto-electrican territory rather than mechanic really - but the explanation on the connector is entirely feasible and might just explain some of the other errors too. Hope it has sorted it for you.

6 hours ago, nta16 said:

Thanks for reporting back.

Battery state of charge is very important to these cars. Sod's Law, I often start with battery state of charge on many issues but not this time - battery was mentioned and by others but not state of charge and recharging this time, that's Sod's Law.

The headlights may seem bright enough and the engine starts easily but the 12v battery state of charge may be too low for the computers and they often throw up all sorts of unexpected warnings and lights, issues - and unseen error codes. There are lots of threads and posts on here and other sites about this on all models.

Get the battery corrected 'coded', there is lots of info for this on this site or just ask even before it is 'coded' check the state of charge on your battery and if necessary recharge it using a suitable battery charger maintainer following the instructions for doing so in the car's 'Owner's Manual' and for the charger maintainer, recharge the battery to full (or at least 80%) on the charger.

The battery may have been weakened by the incorrect charging so do check its state of charge regularly for a while to check it can be charged well.

Even a good battery is best to do very occasional when required preventative (not at or after it is low) recharging using a suitable battery charger maintainer following the instructions for doing so in the car's 'Owner's Manual' and for the charger maintainer, recharge the battery to full (or at least 80%) on the charger to have a long and reliable useful battery life.

VWŠkoda 'Owner's Manual' site. - https://www.skoda-auto.com/apps/manuals/Models

Do not underestimate the importance of the 12v battery (and charging) on modern cars and how much the computer systems are effected, the 12v battery has always been very important but much more so now (even on electric cars) because of the computer systems as well as the other electrics.

6 hours ago, Yorkshiremidge said:

This is the sort of fault where you're into auto-electrican territory rather than mechanic really - but the explanation on the connector is entirely feasible and might just explain some of the other errors too. Hope it has sorted it for you.

Hi both, yes got the battery coded correctly and confirmed it is charging at right voltage now. Spoke to the electrician and he said it was not necessary to manually recharge at moment, went on a long journey (160 mile) and going back to electrician shortly per his request to run some tests just to make sure everything is still ok. No errors showed up and no issues in the journey so all good so far.

And yes, apologies, I meant electrician rather than mechanic although he is an all rounder with 30+ years' experience.

Just glad it wasn't anything major, hoping it stays that way :)

On 01/09/2025 at 12:25, Falaq said:

Thanks for all the replies, car is still at the garage, unfortunately they could not look at it on Friday and were closed on weekend. Will post an update once diagnosed. One thing to re-emphasise, the first thing that happened on both occasions was the EPC light coming on, losing power and not being able to rev beyond 10k and then all warnings about lights coming on. Still hoping it's something small.

Presume you mean 1K RPM - Not 10K!