LightRain

So, just to recap. This only happens when idling? It is worse when warmed up to operating temperature? It brings up no codes and no pending codes? If it only happens at idle, does it improve with more load from ancillaries (AC, blower, etc.)? Also, confirming that you have replaced all filters, coil packs and plugs? Has the engine ever stalled due to these misses? Has the engine been run while monitoring (with VCDS or a scan tool)? Did you try disconnecting each plug in turn, to clarify if it is random or a single cylinder misfire? I'm curious about how the fuel trims behave. These are called STFT and LTFT on generic OBD2 scan tools and something like lambda learned values in VCDS. Any chance of a report on these? A misfire on its own shouldn't cause any damage to the engine itself, depending on the kind of miss, items in the exhaust stream could have their life reduced. It is possible, however, the causes of some misfires can lead to damage so it is prudent to get the problem dealt with as soon as you are able, which you are in the process of doing.

If at first you don't succeed, try and try and try until the customer never returns to you.... More detail on the actual fault code(s) would be needed along with any patterns leading up to your light coming on (if there are any), also more details about your specific vehicle, particularly engine code. Do you have access to VCDS or a scan tool? I'd initially suspect wiring (I usually do), testing the operation of the sensor (with VCDS or generic scan tool) would be a wise move. Depending on the condition of the engine, its sensors and ancillaries the problem could be down to many things, ranging from leaks, to electrical issues to sensor problems unrelated to the O2 sensor. Codes and live data are necessary in order to really know what the problem is and not just make a guess based on gut or "common problems". Another thing that is important to remember, codes are an indication of a symptom not a cause. Normally I'd not ask and assume you went to a good garage but clearly this needs asking, did they use an OEM sensor?

If you want to get them for yourself the place to go would be: https://erwin.skoda-auto.cz/ Someone around here may be willing to send you the relevant pages though. It may help in the meantime to give more details about your vehicle though.

Finland.

Where I live they give the absolute minimum depth for summer and winter tyres as 2 and 4 mm respectively.

You're not guaranteed a code for any problem and when you get a code it isn't guaranteed to be the part that the code represents. Many times a code is just a symptom of the problem, only there to clue you in on where to look for the cause. Did you do what @sepulchrave suggested? Also, it's a good idea to check for vacuum leaks. Do you have VCDS or an OBD2 scanner? Watching your live data while it idles could give you something to go on. Otherwise, in all fairness, you're just guessing at the problem. To be fair you've already blown too much cash on nothing.

Two retirements in as many years, who else can boast that? I'm sure there are others.

Indeed. I really hope they don't go too far down that route. Personally I don't even want standard components. Although, forcing cross compatibility between power unit elements could be interesting. I've always wanted F1 to be as unrestricted as possible. A boundary box, mandated tyres, a limit on energy use per race and very strict safety tests. Leave everything else open. Basically, Can-Am but better.

OK, fair enough, my point on the level of technology still stands.

We have standard bolt patterns at the moment.

I'm with you there. I want scary complex, beautifully engineered machines. It's a sad state of affairs when sports prototypes are higher tech and almost as fast as F1.

You can always tell when a new set of regs are being developed, Ferrari threaten to quit. Can't disagree with the main points though. F1 isn't a spec series and the ever increasing pull that way in the name of "cost control" and "the show" is not good for the sport.

Yeah, voltage checks are the safest, it is very hard to damage anything when checking voltage. Still, some things that you should be cautious of: Be careful not to short any of the pins with your probe and be sure you are in voltage mode on the meter. With the key on and engine off, the sensor unplugged, on the harness side. All tests done with one test lead to chassis (ideally battery) ground. Pin 1 (5V supply) should be a steady 5 V with no significant fluctuation, pin 2 (Ground) should be 0 V (No more than 0.01 V) and pin 3 (signal) will either be 0 or 5 V depending on circuit layout. Next would be with the key on and engine off, the sensor plugged in. All tests done with one test lead to chassis (ideally battery) ground. Use a backprobe or a blunt pin slid into the back of the connector (between wire and grommet) to make contact, don't go piercing holes in your wires and remember that you may not have a good connection, so don't assume problems without double checking. Pin 1 and pin 2 should remain as before. Pin 3 will show a sensor voltage (usually between 0.5 and 4.5 V) depending on pressure differential. Probably low voltage for low delta and vice versa. At rest with a cold engine and exhaust it will probably read 0.5 V. Sucking on the post-filter pipe (the one just hanging there) or blowing on the pre-filter pipe should give you some pressure difference so you can see sensor response.

If it is a 3 wire sensor then the initial tests are pretty easy, basic voltage checks done in DC mode. Do you have a multimeter? I can give you directions if you like.

You could check the wiring harness, if you have a multimeter. This sensor is a 3 wire one right?

Something like those yeah ... The only one I've heard of is the Genius Boost.

Didn't you replace the sensor? It isn't impossible but it is unlikely that a new sensor is dead out of the box. Did the old sensor show the same anomalies? Did you run the necessary adaptations?

Yeah. It probably won't help, but it's a good first step before things get more in depth.

Don't these systems use urea of some description, maybe it says in the owner manual somewhere? The information is out there, could you ask at a local motor factor?

As a first step you could check the throttle body physically. Unplug the connector, check for corrosion or dirt, replug and check the cable as much as you can see for visual signs of damage or contamination. Is yours the same age and engine? If you have a VCDS readout share it with us.

Another alternative would be to get one of those lithium battery boost packs (similar to what was mentioned by pinkpanther). Keep it charged at home and when you need the car take it with you in case you need it. They're pretty small, light, reasonably priced and serve a useful purpose to get a car going if the battery is a bit weak.

Well blow me down, you might be right. http://www.realoem.me/Skoda/CZ/OCT/2011/663/R/2/253/253063#10 https://skoda.7zap.com/en/cz/octavia/oct/2011-663/2/253-253063/#1

I think that's because the sensors are mounted in different orientations in those diagrams. If I were OP I'd be getting into that engine bay and looking for the other part of that open line, if that results in nothing, then I'd be tracing backwards from the DPF/exhaust looking for anything amiss. I'm assuming you replaced the sensor yourself? However if you got a garage to do it, I'd be on to them like a ferret for not completing the job. Anyway, if this pipe has always been missing there's a chance the old sensor was fine, if so maybe you can get a refund on the part.

Has your mechanic at least checked for vacuum leaks? It would be really helpful to have the car plugged into a scanner and checked while running under these conditions, using VCDS or generic OBD2 with live data. Fault codes are only an indication of a specific test failing, there are many problems that could occur just outside of the test threshold that could cause bad running.

As far as I can see there shouldn't be any connection between wheel and indicators. However there is probably a lot of wiring around the stalk that is in close proximity to the wheel. There could be something that is being stressed when turning, a misplaced wire being pulled taut or something. This would fit with problems on input to the onboard power control unit. Depending on ease of access, you can still meter the relevant inputs to the onboard power control unit, to see what happens when you turn the wheel. This would confirm the circuit segment that is causing the problem. Although the wheel action seems to point to control side, there is a lot to be said for a belt and braces approach.