J.R.

Untrue and scaremongering, yes making the changes to the coding will be beneficial but the battery will charge and in time the Battery Management System would recognise the new battery characteristics and adapt accordingly anyway. Did you mean to right "won't charge correctly"?

What mileage are you at? I'm not aware of the 2.0 TDi CR engine going through glowplugs prematurely, the 1.9 PD engine yes, the pre PD in my MK1 Octavia went to its maker after3250000 miles on the original glowplugs with them still working fine. I dont plan to replace those on my current 2.0TDi CR engine unless one fails but if someone knows better and can tell me one is likely to go by X mileage and cause the engine to go into limp mode then I would replace them before then. On the PD all 4 glowplugs having failed made zero difference to starting, brought up no dashboard lights, did not cause limp mode, but for a VCDS scan I would have been completely unaware, I replaced them but it made zero difference.

Fractured field winding excitation wire to alternator making intermittent contact? Why was the alternator recently replaced?

No its designed to make assembly of the vehicle the quickest and easiest (which is making money I suppose) little or no consideration is given to how long or difficult replacement of non service items. The fan on a MK1 Octavia falls out in 30 seconds!

Check the cranking RPM when warm, I bet it is under the threshold for the nonsense software. It's a stupidly high threshold in that the engine will appear to be cranking quite healthily, well any minimum RPM threshold for starting is stupid!!!

Agreed, also how often they get out ie journey length, also their BMI, the seats in my MK1 were perfect at 188000 miles racked up by my chauffeur pal doing airport runs either 25, 50 or 100 miles each way, I was overweight then and wore the seat through in that place, I replaced the cover at the time I became fit and lean, no more visible wear on that and the next cars for 12 years. I put weight on during the confinement and now the Yeti drivers seat is worn in that position, I dont wear jeans so no rivets to catch, cordura type work trousers should slide quite easily, I think my wallet carried in my right rear pocket is what causes the rubbing, if I were thinner again it would not be an issue. @Alban how many kms of the 240000 the Fabia has done have you driven?

Looking at the graph the closing of the throttle valve (I am assuming this is the butterfly) follows a lifting of the throttle pedal. It looks like the feedback loop is positive on deceleration and slightly negative on acceleration. Frankly I'm surprised any of us can drive a car smoothly these days when there is no linearity between the control inputs and the actuator outputs on the fly by wire throttle, jerking and the difficulty in overcoming it (many drivers adapt perfectly unconsciously) is the price we pay for the manufacturers making sure that the numpties don't stall the engine. Very interesting graph traces showing the micro-corrections that we make in control inputs during clutch engagement, this is shown vividly at the beginning, also interesting is the throttle modulation after the 10km/h stumble which you were probably unaware you were making and would have been very different in another vehicle with different mapping in terms of the feedback loop. The inertial lag of vehicle speed vs accelerator and throttle butterfly between 37 and 39 seconds is very apparent, that is 100% emissions reduction coding, vehicles did not behave like that pre EU emissions ratings.

Aircon pump shear plate semi disintegrated with one of the straps flailing. Is the aircon working? Does the noise change when you switch it on or off?

Understood, I think I got your previous explanation backwards in my head, I thought you had disabled the option. It gives me another thing to look at and tweak if need be in VCDS.

The engine would not have developed any boost with one impellor shaft sheared, the other with broken vanes (presumably) and a missing bearing, it would not have been spinning at all. A photograph would make things a lot clearer.

I will look for that byte on my vehicle, I have never liked the idea of freezing air only to then warm it up. I bet your Roomster does not have that option, have a look and see if it has a clutch or the shear plate type pulley, the power lead to the electro-magnetic clutch will be clear to see. I switch my AC off (although I know its not 100% off) often in winter for fuel economy switching it on when I need to clear misting and humidity which is more often than not, if your setting was available to me and I selected it I think it would pretty much stop the demisting working unless I wanted to do it with cold air. Have you tried both settings? What did you experience?

If months go by without the problem manifesting then you should wait longer than one day before deciding to change the master cylinder. Was the slave cylinder a concentric one requiring gearbox renewal? They are the most common cause of clutch problems, they will draw in air but not leak so I can understand if you replaced yours, saw no leakage so now suspect the master cylinder. The master cylinder is very simple, far simpler than a traditional one, it has one piston with a fixed O ring contained within the bore, it operates by displacement, if the seal leaks then the fluid will leak out and be visible, it cannot go past the seal and back to the reservoir like a traditional one. Master cylinder replacement is tricky because you are working blind and by feel most of the time, its very easy to dislodge or misplace the seal for the outlet pipe. I would bide my time.

Well it sure would not be a desired feature. They were not frozen to the screen were they?

Read the first line! I don't know your diagnostic software so could be wrong (VCDS terms are commonly incorrect) but it is saying the fault is in the throttle valve. The throttle valves main function is to create a partial vacuum to draw through EGR gases, it also functions to stop all induction on engine shut down, does your engine shake a little when you switch off? The throttle valve being clogged with schmoo is very common and easy to clean and rectify, much more so than the EGR valve and cooler. Mmmm............... I am beginning to doubt the above now, perhaps the line "commanded throttle actuator control" should not be there at all, then the rest would be describing the EGR valve, both have actuators and position sensors.

Good point, after doing the HID conversion I found there was a parameter in VCDS to adjust the headlight voltage, the default was set low for increased bulb life. The long coding parameter is called headlight dimming, if it is set to "inactive" then the headlamps will receive the full alternator regulated voltage, they will be brighter but will dim at tickover, better IMO than being dim all the time like me!!! Those pathetic projector lamps need all the help they can get.

You have the chocolate teapot projector lamps. Mine were greatly improved by my fitting an HID conversion but the legality of it is questionable and they needed setting much lower than the CT (MOT) machine to avoid dazzling oncoming motorists, even then it happened occasionally. The headlights on my Yeti, just a clear lens with standard halogen bulb are like night and day compared to the projector lens on the MK2.

Incorrect, your AC compressor is a non clutch type whose modulating valve circulates refrigerant 100% of the time even when you believe it is switched off albeit at a reduced duty cycle.

For me no, I never ride the clutch, also I know from VCDS and also having to depress the clutch in order to start the engine that the clutch switch operates way down the travel after the disengagement point. Its just possible that the switch is being falsely triggered, maybe the toroidal magnet on the master cylinder piston that triggers it has come loose, next time it happens I will look at the Maxidot display which would not show what gear the car is in when the clutch switch is operated.

Any VCDS code descriptions that describe the actual fault are purely coincidental! They usually say"open circuit or short to ground" which are two mutually exclusive conditions, the control module measures the volt drop when the circuit is commanded, if it is outside of the set parameters it generates the fault code with a dodgy description.

Projector lens type but with halogen bulbs? Those ones on my MK2 Octavia were appalling, worseeven than a 6v VW campervan with bad earthing and a slipping dynamo drive belt.

And to you too!

You have a carefree way with words, it's called the wrong way Speaking for myself I am not your "mate" and sympathise with those who are. @Occy245 The moderators intervened earlier to remove the worst of the insulting comments, I think its best to leave the contributor to have the last word.

The OP has been unable to use his car normally due to health issues for 3 months and the non use will continue for at least another month hence him asking for advice. One persons normal will be different to another. I am surprised that someone asking for and receiving advice on a car forum should trigger you.

Thanks all, I have a bluetooth OBD adaptor somewhere and an Android phone (head unit is Windows 😒) so will look into it. Agreed yet the measured value of level in litres using VCDS is amazingly accurate especially if you have the twin sender saddle tank, even the guage is very accurate until it gets to around 3/8 of a tank and then the fiddle factor comes in to create the virtual reserve tank that has most people refilling their tanks long before they risk running out. On my MK2 Octavia I ran it dry on the first tank to find the true maximum range, it had done about 80 further miles after showing zero and zero miles remaining, I carried 5 litres in a jerrycan knowing I would run out, after putting that in the tank the fuel guage rose by an appropriate amount, it showed 50 miles remaining, slightly conservative but still super accurate for probably only a couple of cms at the bottom of the tank. It was less than a mile to the fuel station for the proper fill up, during which time the miles remaining dropped every 100m or so, 50, 40, 30, 10, 5, then zero before I had even got there!!!!!!!!

You believe the car has been remapped for more power yet still don't have enough power to exceed 60 mph? 😕 The throttle body is used to create a depression to draw in EGR gases, it also has an important role in stopping shudder on engine shutdown and in the extreme save your engine from destroying itself if there is an oil leak in the turbocharger. I would never drive a diesel without a throttle valve or some shut off device, I suspect that yours still fulfills the secondary purpose but not for EGR, that is the situation for my vehicle with an EGR emulator/simulator, if the butterfly is sticky or the geared linkage to the potentiometer damaged you will still get the fault codes and limp mode. That is to say unless the mechanic fixed the original problem you will still suffer from it I believe.