Hi All

This is my first post on Briskoda Thank you everyone for this great resource, I am located in rural Southwest France

We have a lovely if not well used LHD Octavia and it has (I think) developed a serious electrical / electronic problem

The car has done plus 300k kms, it goes like stink when it ran last, its got a fairly good service history before me and I service it 

The car belongs to my wife its her third Octy L&K etsate so she has a fairly good feel for the car. I drive a 30 year old Defender 90. This potted history is taken from her notes. Important note autumn had set in properly and along with it came regular heavy rain!!

1) The issues started last October (2023) where occasionally the dials on the dash would behave completely randomly plus warning lights flashing. The car cut out occasionally but would start again. I disconnected the battery for an hour or so and afterwards it behaved for a while.

2) Then  in November on the 11th the coolant level warning light flashed on the dash and alarm sounded, checked level plenty of liquid. Later in the day the car just stopped following random dials behaviour  and would not start, then the oil warning light and alarm cam on, checked oil level little low topped it up and car started again.

3) Over the following few days the car threw up coolant warning light and alarm checked the restarted car went away for a bit but continued to randomly come on again with the same process ocuring.

4) 15th Nov set off for the next village for nurses app car quite just beyond our village rolled into cemetery carpark would not start hazard lights would not work. had to tow car home with Landrover.

5) The car was normally parked in our usual parking spot on the edge of the wood, so as part of trying to find out what was wrong I checked the scuttle panel for debris. It was completely covered with leaves not just new ones but also old slimy sticky ones at the bottom. I mean properly covered!! all side all the way along the bottom of the windscreen and up again the bonnet. So I cleared out the all leaves flushed out the area beneath (where the wiper arms are with a hose and compressor but didn't open it) again disconnected the batter for an hour or so. Also changed where we parked the car to under a roof from then on.

6) Now this worked quite well for a bit end of Nov and all through Dec and Jan, no warning lights for a while started fine etc. However when the frost set it the fuel gauge and computer predictive remaining kms began to misread / contradict one another, or wildly miscalculate remaining fuel randomly even after filling up. but car was running OK 

7) 2nd Feb 24 car starts fine journey of 20 mles to a town south of us, with a stop along the way no problems initially. when trying to start the car for the return journey it coughed / faltered when starting but car started. Drove 5kms stopped to pick up drinking water again faltered on starting meanwhile no warning lights had been showing. Then the central locking went mental and locked an unlocked the car multiple times while driving, had to stop in layby switched off engine took key out opened drivers door door. Restarted car again faltering on start up. Had a second stop to make on return journey again faltering on start up but started and got home

8 ) Final journey, same day, school run to collect little one, car again faltered while starting drove 10kms to school. Again on trying to start car faltered drove less than 1km to the park stopped kids played for 30 mins then tried to start but faltered for longer now not sure if it would start however it got going. Nearly reached home but just outside our village the battery light came on, car faltering / running rough, slowed down for junction but loosing power realised car was dying rolled off junction to side of road and car died. Towed it home

9) Cannot start car, I have opened up the scuttle panel found more debris cleared drains damp cables leading to ECU box plus connections appeared damp. Found water in drivers footwell pipe from sunroof actually disconnected let alone blocked. Damp under dash below Instrument cluster. 

10) Following repeated attempts to  start it I finally resorted to buying VCDS and ran the auto scan the latest fault codes are attached as a PDF

11) As a complete newby novice gullible fool with ZERO experience of Skoda VAG fault codes and fault finding and interpretation I royally misinterpreted the Output from the VCDS and for some reason bought and installed a new cam sensor. Oh joy since I had recently replaced the cam belt before all of this had started and yes I eventually realised the belt had to come off again to replace the sensor. Total waste of time!!!! Car wont start!!!

12) Mechanically speaking Im ok, I do all the work on the Landrover and my Renault Messanger truck plus many hours helping others with such vehicles. But when it comes to cars with such complicated electronics I'm out of my depth. To be fair I have regularly rebuilt my PC and built new PCs from scratch so sort of feel I should have a go. No success so far.

Does anyone have any ideas, The fault codes are obviously from a car that wont run so I assume that limits the useful info.

The drivers seat is out, the carpets are lifted the insulation is carefully cut and taken out and dried. The engine ECU has been removed and very careful opened to see if there was corrosion inside following threads on Youtube showing how they can let in water through the breather over time. That is inconclusive since I wasn't brave enough to get the second half of the cover off to actually expose the area where the corrosion would be (I tried but it wouldn't come) Yes I know, but I was very very careful 

I haven't open or removed the Canbus gateway, I've followed a thread where someone found this to be corroded internally following a water leak under the windscreen?

Any ideas would be gratefully received

 

2008 Octavia 2ltr PD Fault Codes.pdf

According to scan it's an AZV code engine, not ASV.

If I get a chance this evening I'll view the rest of the scan and circuit diagrams to see if anything leaps off the page as worth investigating. 

 

Could be the throttle-body/anti-shudder valve sticking in shut position sometimes, off the top of my head. Ever cleaned that out? On second thoughts, that wouldn't create the same electrical chaos as you're seeing, just the reluctance to start.

Edited 23 May, 20242 yr by Breezy_Pete

Hi Breezy Pete

Thanks for taking the time to have a look at my post

Yea your right thats a typo on my part definitely an AZV

Where is the throttle body anti shudder valve located, I assume somewhere on the air intake pipe I assume its electricaly controled 

 

There are a number of reports in your chart of intermittant low voltage. Some previous posting have said this can be caused by a corroded earth cable or by corrosion on the rear of the printed circuit board near the battery that distributes power around the car.

 

To check the later, disconnect the battery then remove the printed the circuit board to view the other side. This is the board next the battery that contains additional fuses. Some have also found corrosion on the fuseholders.

 

In view of the rotting leaves in the bonnet area then this is my best guess but corrosion can occur anywhere including earthing points and exposed cable ends.