Hi,
I had this "no SOS" problem as well (67 plate Superb SEL Executive).
It started for me on a camping trip a couple of weeks ago and the culprit was (i believe, and this thread sort of confirms it) a low battery.
Also confirming the cause, I replaced the previous EFB battery last week with an AGM (Varta E39 - #570 901 076) and the fault disappeared.
I was also reading this thread and others about the new-battery-coding-issue and can confirm that mine needed to be recoded, or at least, lots of faults appeared after the new battery was inserted and the (local) garage needed the VCDS to fix them.
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I've had my concerns about the EFB battery that came with this car; it was bought last October with 18k on the clock but I noticed that the start-stop didn't work quite a lot of the time. Reading around in Briskoda led me to suspect that the battery wasn't really up to it and battery readings (often as low as 11.6v at rest) suggested that the battery was struggling. I realise that modern battery diagnostics are more complex than an at-rest reading, and am also conscious that there's not been a great deal of mileage (=battery charging) during lockdown etc. since OCtober 2020, but the camping trip experience resolved me to get the new battery in asap.
Specifically, after driving 64 miles over 1hr 15 mins, I pumped up two single air mattresses with the engine not running, and then put the engine on to do the next two single mattresses. The car then said "your battery is very low, you should go for a drive to charge it up".
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The AGM is now in, the SOS error message is gone, the start-stop works all the time, and the local garage very kindly installed the new battery (that I had delivered from Tayna) free of charge. All good.
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NB - not long after the purchase last October, I took the car back to the Skoda dealer from whom it was purchased to check the EFB battery performance and they said it "was all within parameters" and would not replace it.