I have a facelifted 2018 Octavia and I noticed last night that the rear washer wasn't working although I could hear the motor running.  I checked it again this morning with the same result.  But later in the day when I checked it again, the jet was spraying fluid from the bottom of the 2 slots on the wiper arm but not from the top slot.  This isn't due to the jet freezing as the weather last night wasn't particularly cold.

 

I am guessing that the jet in the top slot is blocked and the problem isn't due to a disconnected pipe as the spare wheel well is dry and the jet in the bottom slot is working anyway.  My question is what is the best way to try to clear the jet in the top slot please?  I am still under warranty but don't want to waste a full day whilst the dealer looks at this.  By the way, I have always used VAG screenwash at 50% washer fluid and 50% water.  Many thanks.

Interested in this as well. I also have a facelifted 2018 Octavia with the exact same issue you describe except i didn't have fluid coming out at all. I initially thought the hose was disconnected and started open up the boot lid plastic 'cover' to investigate. All pipes were connected. 

I even had someone sit in the boot whilst the pipe was disconnected from the motor, holding a bucket to make sure water was getting to the motor- which it was.

I then put a needle in to the nozzle (through the wiper arm) and wiggled it about to release any blockages within the nozzle itself. This got the top nozzle working but no such luck on the bottom; it just sort of drips out of it. For now I'm happy that I can clean the rear window but I will come back to the bottom nozzle in time. Like you I can't be bothered taking it to a dealer for a full day, 

Managed to sort this.  Once I put my glasses on, I could see the holes in the 2 jets.  I used a straight pin approx an inch long and simply pushed it into the jets.  The pin went in almost all of the way with a bit of pressure.  End result is that the washer seems to work  OK now.

Apologies for resurrecting an old thread, but for those still having problems, I discovered that you can also remove the end cap of the rear wiper (At least on hatchbacks) and then pull the actual rear washer nozzle off. This makes it easier to unblock it via pins or other means and you can test if the washer pipes are still connected. If washer fluid sprays out without the nozzle on, you know the issue is there.
Probably stating the obvious but that is what I did and managed to fix a lot of washer problems that way.

A good plan to lever off jet cover from fat end and prise off jets. I also soaked them in vinegar. Take care when refitting cover. make sure the two end hooks are properly engaged. I use rain water for refilling and recommended fluid. 

Mine blocked a few months ago, gave them a prod with a pin a few times and seems ok now.

Anyone know how to deal with this problem on an Octavia where it is difficult to see that actual nozzle hole? I had to get a small mirror to actually see the hole, but it is very awkward to hold the mirror and poke around in the hole, especially as the hole is at an angle. How do "proper" mechanics do it? Is there a special tool involved?

Just now, reincheque said:

Anyone know how to deal with this problem on an Octavia estate where it is difficult to see that actual nozzle hole? I had to get a small mirror to actually see the hole, but it is very awkward to hold the mirror and poke around in the hole, especially as the hole is at an angle. How do "proper" mechanics do it? Is there a special tool involved?

 

1 minute ago, reincheque said:

Anyone know how to deal with this problem on an Octavia where it is difficult to see that actual nozzle hole? I had to get a small mirror to actually see the hole, but it is very awkward to hold the mirror and poke around in the hole, especially as the hole is at an angle. How do "proper" mechanics do it? Is there a special tool involved?

In my case, it turns out you can carefully pull the end cap of the rear wiper arm off and then pull the actual nozzle underneath off, making the process a lot easier.

Just now, hhcd80 said:

In my case, it turns out you can carefully pull the end cap of the rear wiper arm off and then pull the actual nozzle underneath off, making the process a lot easier.

Thanks. In the estate, the nozzle is incorporated in the brake light under the spoiler and not in the wiper arm..😣.

3 minutes ago, reincheque said:

Thanks. In the estate, the nozzle is incorporated in the brake light under the spoiler and not in the wiper arm..😣.

Ooof. Unfortunately not sure about that one. Sorry.

This video is for the Golf, but maybe relevant.  Shows the rear washer.

 

Cool! Thanks for that! V interesting! Any idea what tool he used to prise out the unit?

This video helped me with mine: 

 

 

Thanks for this.

Unfortunately, as I've just found out to my cost, the VW video fails to mention the fact that the light unit needs to be substantially detached from inside the boot lid before you can "simply prise it out". This involves removing the interior trim from the boot lid. Now I need to replace the light unit...