J.R.

Its the immobiliser, on my MK2 it ran for a couple of seconds barely. The glass tube is the RFID chip so will be foutu and cannot be copied. Did you have another working key that the new keys were cloned from? If not then its a main dealer job at IIRC around £350 although some of the more dodgy individuals may have the means to over-ride the immobiliser settings AKA steal your car or any other, I would not be wanting to deal with them and would go the main dealer route which will disable any other keys that may be out there, it's not a bad price really, better than replacing lock barrels and gives you the ultimate security. Another option could be a matching ECU, instrument cluster and keys from an identical scrap vehicle, likely to cost more than the main dealer route and bring loads of grief and additional programming expense with it.

This sounds like a key moment, were the RFID chips swopped from the old to the new keys or were they new keys from Skoda? If the latter was the instrument console reprogrammed to delete the old RFID data and to accept the new?

No coils or coil wires then on a diesel hence the confusion. Your problem is almost certainly immobiliser related, had the instrument cluster been removed before the problem or were there any signs of it misbehaving? You need to have a VCDS or similar scan to reveal what part of the immobiliser system is not working or misfunctioning, I reckon it no longer recognises your ignition key(s), did you perhaps replace the keyfob or its battery before the problem? In any case playing parts bingo is achieving nothing other than emptying your wallet.

One other question, does this problem occur after you have done a spirited change into 5th gear whilst pressing on? By that I mean accelerating hard to high revs in 4th gear then a fast gearchange and onto full throttle in 5th gear like you might do when overtaking traffic. Under those conditions the clutch peak torque limiter will cause momentary or longer clutch slip (a crazy system) one isnt normally looking at the speedo display but it will not show the selected gear until everything has stabilised.

I think there is little to no possibility that the ECU is at fault, it cannot be recalibrated, I understand why you may have asked for that but there response just further illustrates their ignorance, you would get more sense out of a goldfish. For me it would be the clutch sensor or the neatral sensor and/or the wiring to/from them. Also the gearbox output speed sensor if there is one, I might have made that up but I recall disconnecting the wiring from it when removing the gearbox for a clutch & DMF change, its the sort of thing that may not have been correctly reconnected, the wiring strained if they forgot to disconnect it during a clutch change (has yours been done?) or exposure to the road dirt etc. The magnet inside the clutch master cylinder which operates the external reed switch can get covered in an unidentifiable magnetic schmoo, it can only be revealed by cutting the cylinder apart. Is your clutch pedal actuation perfect? No sticking in the down position? Does it return with the control loading spring assistance to the top position?

I agree with your reasoning and with dismissing the battery as the easy/cheap remedy, whilst you are probably correct in it only leaving the pump unit there are other possibilities like wiring, Petes suggestion is very plausible. Thankfully not all! 👍

Instead of saying "look we dont know what is causing this" they are grabbing at straws like the software update and inventing possibilities that if they had any logic or understanding of the vehicle would realise are simply stupid. There is absolutely no connection between the 5th/6th gear selector fork and the calculation that the ECU makes to decide what gear the vehicle is in based on RPM and gearbox output/road speed. Whatever you do please do not authorise them to remove and dismantle the gearbox, it will not resolve the problem and will likely leave you with many others as their competence appears to be limited to downloading unnecessary software updates. They do however have an A+ in customer service Bravo Sugar.

If you do not post rubbish that may waste peoples time and money then every day will be a rest day for you. The OP asked To which you replied that you cannot help with that in order to launch into the usual lengthy battery and computer discourse including telling him that he needs to change the battery which at £311 he he had expressed he was reluctant to do unless it was definitely the cause. The OP has not chosen to go a DIY route in regard to the alternator pulley: I ask for a second time - "Please explain what would you have wanted me to have learned from recent traumatic events."

Whilst we don't yet have confirmation of what was the cause I thought I would post one of the adages from my mentor that has stood me well over the years. It's better to be imprecisely right than precisely wrong!

Good point.

Yes I am on the journey back to health. Please explain what would you have wanted me to have learned from recent traumatic events. I only ever comment when your obsession causes you to write rubbish like changing the battery as a cure for alternator noise, the rest of the time your battery and VAG computer focussed verbosity simply amuses me.

I bought my accident damaged 2015 2.0 TDi Outdoor in 2020 for £3200 with 79K on the clock. It cost £800 to repair to an acceptable condition, it will never be a class 1 car and it takes a lot of abuse, minor bodywork damage mostly just touched up and compounded, 3 x dashboard & steering wheel airbags deployed plus seatbelt pretensioners, reconditioned dashboard fitted which has invisible repair where ruptured by airbag. It has now done 125K miles, has never let me down and gives excellent fuel economy for a flat fronted brick with 4wd, I no longer hear or notice any regens after having the emissions fix rolled back. At the time it did not seem a great deal after I had finished the work, the 2 Yetis that Blackbird bought bear that out but it was a fraction of the cost of one in France. I cannot believe how much they have gone up in price since then, its academic to me but I dont feel so bad now about how much I spent. Also if I was not bored and surfing for a project I would never have owned a Yeti and not realised what a great vehicle they are.

A service is just an excuse to hold the car to ransom while they practice their creativity with "brakes 90% worn" etc.

That does not sound encouraging, there is normally a seperate electrical pump for the heater. The guage going up to 120° I can explain, you probably know that the readings are fiddled for the needle to read bang on 90°c over a wide range, when it moves it moves a long way! When you stopped to remove the connector the engine was probably over 90°, there would then have been heat soak while the engine was not running, I can understand it going up to 120°c quickly but if it dropped down again quickly then the water pump is now circulating. I am a bit concerned about the cold heater though, that sounds like a Silkat blockage, have you looked in the reservoir and at the colour of the coolant?

I drove past Limoges on the way back yesterday, if you are 20 minutes South then you are probably not a long way from me if I can help in any way. I have VCDS.

Once again your obsession is running away with itself. The noise you have is almost certainly the alternator pulley one way sprag clutch coupling especially as you have replaced everything else. You will notice that the long side of the belt will be oscillating when the noise occurs. A cheap and easy job to do with basic tools and no need to remove the alternator.

What sort of net profit do you believe a trader makes on a second hand vehicle in order to "factor in" a £7500 repair bill 3 years after selling the vehicle?

Whilst heel and toeing with a glass of water on the bonnet!

The gear indicator works using a calculation from the engine rpm and I think the gearbox output shaft but might be the wheel sensors. Clutch slip will screw it up as will a faulty clutch position sensor or riding the clutch which will give it double trouble!

Am I the only person in the world that doesn't want to drink from a cup while he drives his vehicle? I drove 600 miles today, 14 hours door to door and stopped for 3 coffee breaks, the coffee drunk with a snack sitting at a table. I bet rare breed grumpy monster cup OH drives less than 5 miles with her drink 🤣 At one coffee stop I watched bemused as a young mother with baby in some freakish moon buggy like contraption spent 15 minutes to extracting her child from the contraption, install him/her in the child seat, then collapsing the contraption to load it in the boot, they will have spent the same time getting out so 30 minutes plus whatever they did in the services which was no more than 10 paces from her vehicle parked in the space allocated for the purpose. They must spend an hour doing the same for a 5 minute drive to the shops and back. As a child I was either carried on my mothers hip or my fathers shoulders and dumped in the external dicky seat of their Morris 8 Tourer, my elder sisters had the rear seat inside the cabin, no seat belts so it would have taken all of 10 seconds to load me!

Yes it will be good to learn, my only experience was a change of ECU (a remapped one) which had the immobiliser function disabled as otherwise the vehicle would not have started due to the data stored in the instrument cluster. I think the ECU and instrument cluster together can be taken from one vehicle and used on another but not individually, it sounds like the new instrument cluster can be recoded copying your immobiliser data.

That will be interesting to learn. The changes of crankshaft angular velocity at low revs I think will be far more on a diesel engine than a petrol although maybe with the larger flywheel and harmonic bi-mass front pulley that is not the case.

What did they do to fix the random battery discharge?

Ok, I forget that Fabias are often simpler and the tech can lag behind other VAG platforms. What I spoke of was correct for a MK2 Octavia 6 years earlier than your Fabia. If he manages to overcome the immobiliser and mileage issues please let us know.

3D mapping in conjunction with the knock sensor will always apply the maximum ignition advance on part throttle openings to minimise fuel consumption. In the good old days it was achieved in a very poor manner in the distributeur by the vacuum advance mechanism.