Breezy_Pete

6-valve or 12-valve?

Seems like the right thing to do.

Check to see if the red battery symbol comes on when you turn the key to the position where other lights come on in the instrument display.

No, the oil filler cap, where you pour in oil to top-up, or refill oil after draining it. The 'bayonet fitting' refers to the 90-degree turn-to-lock type mechanism. Shouldn't get messy, as it should only take a few seconds to do the check.

Presumably by re-soldering the damaged solder joint of 'one of the 2 main capacitors' inside the ECU. If you open yours up and take some photos of what's in there, I can probably guide you to a solution.

Spent a happy afternoon disassembling the front passenger door on our 05-plate Fabia, after repeatedly observing the following behaviour. If the car is unlocked with the fob, and just the front passenger door opened, it re-locks itself after a short while as if it doesn't know that door has been opened. Not 100% of the time, but more and more often. Also; and noticed as long ago as a year back, is that sometimes when driving, the car either attempts to or actually does lock itself, partially or completely, and sometimes immediately unlocking again, often when braking or cornering. Locking and unlocking behaviours without any active input. All a bit random. I've made previous attempts to fix this second symptom, but all unsuccessful. One involved repairing wires with cracked insulation in the drivers side a-pillar bellows, together with cleaning up and replacing some pins in the connectors at that pillar, as there was some corrosion evident, likely caused by water ingress past a poorly re-fitted rubber boot/bellows. Another was inspecting and 'contact cleaning' the same pins/connections on the passenger side. Yet another was an extremely optimistic (i.e. pointless) spraying of contact cleaner into the general area of the door-open microswitches, with no disassembly, just through the holes on the back edges of the doors. For today's attempt, I was expecting at least the door open microswitch would need replacing, but wasn't really sure that that alone could explain both symptoms. Not done enough testing at all to be sure that what I found does cover both, but optimistic for now. Here's the lock, fully removed as per @Tech1e's guide for window regulator replacement; plus a bag containing a genuine replacement microswitch. I didn't fancy grafting that switch into the existing wiring, following a bad experience of having to revisit this work on my Polo after trying this shortcut. Two inline crimps are supplied with these microswitches to make such a technique easy. Soldering the wires directly to the pins of the connector on the topside of the circuit board was successful back then, on that one, at the second visit. Can't really remember why I didn't completely remove the old wiring from the board, possibly reluctance to do that final bit of disassembly to get at the reverse of the board, 'twas a few years ago, I forget. This is what the board looks like before complete removal. And this is the underside after removal, showing the connector connections and microswitch solder joints, all coated in a thick layer of brake-cleaner-resistant conformal coating of some type. I couldn't really see much of the joints through this dark brown coating, but did think I was observing a little more movement than expected - when waggled gently - of the connector relative to the board. Cleaned away by scalpel a few bits of the brown coating to get a better look, and one joint was particularly grim. It's the earth connection, which goes to the door open microswitch and some other places... Here's a very brief video of it being waggled: 20200910_155143.mp4 I swapped the new microswitch in as well, as it made no sense not to. Everything's pretty much back up together again now, but only 3 out 10 rivets replaced, and no door card yet. I will await feedback from the owner on both types of misbehaviour before finishing it off, I think.

Not sure if it's similar to the one on the 3-cylinder HTP engines, but those have a spring up the middle of the tensioner that means tensioning push never goes to zero.

Dry yes, new no. Wheel bolts are clearly reuseable, so giving a torque figure that only applied to brand new bolts would be non-sensical. I always clean the threads of mine thoroughly before refitting (dry).

Skoda torque figures are for dry threads aren't they? So overtightening inevitable if same torque is used on lubed threads.

EGR isn't unproblematic, it's true.

No, normal flywheel.

Why not stick your phone under and slightly behind there and take a photo upwards to see what it's bending round?

Not sure what a cover would do there? What makes you think there's one missing? The photo in this listing suggests yours is as it should be: https://www.ebay.co.uk/itm/Skoda-Yeti-2013-2017-1-2-Petrol-Bare-Engine-CYVB/273637688066?hash=item3fb613c302:g:xnkAAOSwJaxcLeJw

Illegal to vent crankcase fumes to atmosphere, as well as antisocial and potentially rather dangerous for other road users if oil drips onto the road.

No they didn't, as MOT doesn't measure NOx. It was Type Approval emissions testing that they gamed, in EU and US, different level of testing to MOT. They still had to build cars that were capable of behaving themselves 'just for the testing'. Tuners don't have to even bother with that. Legally speaking, in the UK at least, it's illegal to do anything (or presumably to have anything done) to your car that makes the emissions worse than they were at type testing, but that's hard to police, to put it mildly.

Also, some of the emissions limits that manufacturers must meet cause conflicting constraints, causing compromised fuel efficiency. For example, modern diesel engines could be much more fuel efficient if there were no limits for NOx output. Tuners are not so bound by regulation; arguably not at all, as long as the results of their tweaking don't cause MOT issues (NOx is not measured at MOT).

Dunno, but ebay has plenty. Not recommending this supplier per se (good feedback numbers though), but these came up easily enough on a search for "m14 x 35 radius seat" or something along those lines: https://www.ebay.co.uk/itm/20-x-wheel-bolts-M14-x-1-5-Radius-Seat-35mm-Thread-length-17mm-Hex/252591760289?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D2%26asc%3D20160908110712%26meid%3D5770829ea498418db5e1d2af69431d4d%26pid%3D100677%26rk%3D3%26rkt%3D30%26mehot%3Dnone%26sd%3D264525367038%26itm%3D252591760289%26pmt%3D1%26noa%3D0%26pg%3D2386202%26algv%3DSimplAMLv5PairwiseWeb&_trksid=p2386202.c100677.m4598

Factory alloys use radius seat bolts, so doesn't look promising.

I can only see one pressure switch listed here: https://skoda.7zap.com/en/cz/yeti/yet/2014-779/9/919-919041/ item 8 What colour is the warning light, red or yellow? (Low pressure or low level) Smell your engine oil to try to detect contamination/dilution with diesel. Be especially suspicious if the level appears to increase instead of decrease with time.

Fuse 40 in the end of dashboard cabin fuseholder, I think, 40 Amp rating.

Gimme a minute or five and I may be able to tell you.

There's a direct connection from switch to motor when the switch is in position 4, max fan speed, so that would seem to rule out the resistor as the probable fault. You've checked the fuse, presumably?

Oh, and the cam sensor oil leak might be a clue that the crankcase ventilation isn't working correctly. Try removing the oil filler cap while the engine is running. Note whether it feels like it is being pulled back down as you release the bayonet fitting, or being pushed away upwards. This may well affect how the engine runs at idle, so don't be surprised if you hear a change as you open it.

Another thing that looks non-factory is the main battery negative cable. Can you post a better photo of the end that connects to the car body? The battery post end doesn't look 'normal' either. It may be perfectly OK as it is, but worth checking I think.

Yes, except they're bolts, not nuts I think.