Skoda Octavia Mk 3 will not start

[Eddie5768]

Going down the M69 all the warning lights on the dash came on, but the car kept going fine. After 20s dash went back to normal. After another couple of minutes I lost everything on the dash including the speedo & rev counter. After 20s dash went back to normal. No problems then for 10days (including a wkd in York for the Snooker UK Championship). My wife took the car out on Monday and it happened again. She turned back and parked on the drive. Nothing now happens when I try to start the car. All other electrics seem to be working fine except for the driver's door which will not lock. 

 

Does the car not start because it thinks there has been a break-in?

 

 

[Ecomatt]

First port of call is to get it scanned as it will have raised a fault code even if it isn't static. The best way is either through vcds, obdeleven or a VAG specialist.

Equally if you have any dealer warranty I would let them sort it as I do not know what year your car is.

[Eddie5768]

Thanks Ecomatt. I've been waiting for a mobile Automotive Electrical Engineer who I have used before, but unfortunately he's now at hospital with his dad who has COVID Pneumonia. 

Interested to know the connection between the driver's door central locking not working and the fact I cannot start the car. I can't think of a logical connection between the two

(excuse the pun).

[KenONeill]

27 minutes ago, Eddie5768 said:

Nothing now happens when I try to start the car.

Does the battery light come on when you switch the car on? I've got an idea, and this answer will either confirm or contradict it.

[Eddie5768]

No - the battery light does not come on when I turn the key.

 

[KenONeill]

3 hours ago, Eddie5768 said:

No - the battery light does not come on when I turn the key.

 

Cheers. At that rate I think you have a flat battery caused by a failure in the alternator control wires.

[Eddie5768]

Not sure about a flat battery. Doesn’t explain the dash lighting up like a Christmas tree and then dying intermittently. Also doesn’t explain why one door out of five is not locking. All lights are working inside and out. Infotainment system is working just fine.

[PipH]

If the dash is dead the car won't start.

 

The dash also has the immobiliser chip in which has to communicate with the ECU to allow the car to start.

If the dash has no power to it, the ECU won't allow the car to start.

 

Try banging on the dash top to see if any response.

 

Could be a loose connection.

 

 

 

[nta16]

Up to you either check the battery's state of charge or don't, everything  you've mentioned includes battery power, or lack of as may be the case.  Or you got an electrical fault - you've been given two suggestions already here's a third loose or bad battery terminal, cable, wire, earth wire/cable or connection or other electrical or computer connection wire/ cable.

 

If the battery gets too low it may still be able to start the car and the lights might seem bright enough but it can still be too low for the computers and they will throw all sorts of wobblies, their programs are invasive and intertwined.

 

Not much cost or effort to check the battery or recharge it - even if it's not the battery a low battery will hinder sorting starting and electrical issues whereas a fully charged battery will help with finding starting and electrical issues.

 

[nta16]

The idea of banging on the dash top is more humour to me - but who knows. 😄

 

Edited 10 December, 2021 by nta16

[KenONeill]

1 hour ago, Eddie5768 said:

Infotainment system is working just fine.

You didn't think to mention this before!!

[Eddie5768]

Thanks all for your replies. All battery terminals are fine. If the alternator is not charging properly it should have shown me on the dash (before the dash failed as I haven't run the car since). I'm trying to understand the logic of what seem like random failures as it should theoretically take me to the source of the problem, but I'm scratching my head. PipH, thank you for letting me know about the immobiliser and dash to starting relationship - very helpful. It doesn't seem to explain why the driver's door won't lock though?

 

More info from this morning:

No change at first, but after opening the bonnet (irrelevant I am sure) the dash lit up, the driver's door started to function and the car started. Not good news as it means I have an intermittent problem which is harder to find. It does however point to a dodgy connection somewhere. Had to go indoors so switched the engine off. Came back out and situation had changed. The dash lit up and the car tried to start, but there didn't seem to be enough juice and the dash lights flickered. So maybe it is the battery after all, although it doesn't quite fit the logic. Green Flag are on their way so I'll get the battery tested.

[Eddie5768]

PipH, I tried banging my head on a brick wall, but that didn't help either 😄

[nta16]

This is a VW - VW made their computer programs over-complicated, they are very invasive and, like all other car company computer systems very intertwined.  If the computers say get low power from low car battery and even if not they can get their panties in a twist and then cause all sorts of problems that may seem quite random.

 

Or it could be a bad electrical connection of some kind, possibly even to one of the computers.

 

Have my video of the day to perhaps help you understand the logic of (VW) vehicle computer programs, give you something to watch until Green Flag get there.

 

 

[Eddie5768]

Brilliant video nta16. I'll be following you from now on. I feel I have a new best mate 😉.

[nta16]

Let's wait and see what the resolution is to your fault, hopefully it's not your fault, anything electrical and I will claim a reward. 😊

 

If it was the RAC coming out to you they sell batteries so seem to find a lot of batteries that can't for some reason be recharged.

 

[PipH]

" More info from this morning:

No change at first, but after opening the bonnet (irrelevant I am sure) the dash lit up, the driver's door started to function and the car started. "

 

I'm pretty sure the relationship between the door module & dash both not working at the same time won't be irrelevant.

 

They may well share a common power source.

 

But without a wiring diagram I can't help further.

[nta16]

4 hours ago, Eddie5768 said:

after opening the bonnet (irrelevant I am sure)

The windscreen wipers don't work with the bonnet raised on my wife's Fabia Mk3, hope that helps to show how integrated the systems are, there lots of other examples but none come to (my) mind at the moment, perhaps at 2am.

 

 

[KenONeill]

2 hours ago, nta16 said:

The windscreen wipers don't work with the bonnet raised on my wife's Fabia Mk3, hope that helps to show how integrated the systems are, there lots of other examples but none come to (my) mind at the moment, perhaps at 2am.

 

 

Also @Eddie5768 There are some faults that can be at least temporarily reset by opening the bonnet. For example, the low oil level light.

[Eddie5768]

Well it seems I have been trying to solve the problem on my Mk3 Octavia with Mk1 logic! You've all been telling me that the electronics are so mind-boggling that normal rules no longer apply so I went back to basics in spite of the symptoms. I measured the voltage of the battery at below 10v and decided to replace the battery (5yrs old). After all with extra complication must come extra battery stress. Stop-Start battery available on Monday.

 

There is still a possibility that I have a faulty alternator, but having taken two long journeys over the last 10days I still think the dash would have shown this up. Anyway one change at a time complies with the rules of problem identification, albeit a bit costly if wrong.

[nta16]

Well flat battery has perhaps been mentioned and alluded to once or twice - but below 10v!?  Was that when you were cranking it over or at battery positive post clamp and body earth point.  10v and the battery probably didn't have enough energy to power the low battery warning messages.  😄

 

If you were using a cheap digital multimeter I've found they soon give untrustworthy figures, mine is a not so cheap but not expensive one and it gives very optimistic figures, but even that would struggle to raise a smile for a real 10v.

 

If you're doing a like for like battery swap then you could get away with the car's computers eventually working things out for themselves but if you're going to change the battery type or reasonably significant change to power and capacity then you'd be best to recode for the new battery as soon as you can but not out and out wave your arms in the air panic, well not too soon anyway.  🙂

 

If you haven't got a higher level scan tool then the computer may take a little while to fully sort themselves but if you don't have any other faults they will settle.

 

Let us know how you get on but do remember a battery is a store so even a new battery can be depleted.

 

Edited 12 December, 2021 by nta16

[Eddie5768]

It's an old multimeter, but laboratory accuracy.

 

I would normally buy an Exide or Bosch battery, but in the end bought from Halfords (5yr guarantee). They will fit it on Monday and recode at the same time. Then I'll get the alternator checked. Even if the alternator has a fault it might well have damaged a 5yr old battery. For piece of mind I need to have confidence that the problem has gone away.

[nta16]

Love it!

 

On 12/12/2021 at 12:47, Eddie5768 said:

but laboratory accuracy

Yes but when was that last confirmed.  Always test the test equipment, and tester.  😄

 

 

On 12/12/2021 at 12:47, Eddie5768 said:

Then I'll get the alternator checked. Even if the alternator has a fault it might well have damaged a 5yr old battery. For piece of mind I need to have confidence that the problem has gone away

Too true otherwise it could damage your new expensive battery and coding.  You missed out though as you could have gone to Tayna for battery then nipped to Northampton had your battery coded and alternator checked and compared your old multimeter readings to a not too cheap modern digital multimeter and iffy Ring 12a SmartCharge with Battery Analyser and modern scan tool and picked the figure you felt most confident with, or liked. 

 

What did you put the probes or clips on to get the 10v? 😄

 

Edited 15 December, 2021 by nta16
spelling

[Nogrille]

On 12/12/2021 at 12:47, Eddie5768 said:

They will fit it on Monday and recode at the same time...

Any update?

[Eddie5768]

New battery fitted by Halfords. I would normally do this, but as they recode the battery at fitting it made sense. One more thing to cross off my list of things I have always done. All now good and alternator charging fine.

 

Thanks for your help everyone. Lots lessons learnt.

 

@nta16I am calibrated every day by my wife 😄