Breezy_Pete

I forgot the health and safety briefing - mind fingers/hands when doing the linking; make sure they're not amongst the fan blades!

Scroll up to the post I wrote 8 hours ago.

Wait for input from others before embarking on anything as major as cambelt/waterpump work. I don't know a lot about diesel engines. Is it driving the same performance-wise? If it's way down on torque and power, check that no-one's swapped in a 1.2 petrol engine when you weren't looking, 'cos they warm up fast like that. 😀

Fast coolant temperature rise might be indicative of a water pump problem; any idea how old that is? If it were thermostat failing to open, I don't think you'd see such fast rise on a diesel, or for it to stabilise at 90-ish? No coolant loss?

Good result, hopefully that didn't cost you too much?

To answer your question, disconnecting anything shouldn't cause any programming issues, but it may be wisest to disconnect battery negative lead and wait a few minutes before disconnecting anything else.

What is the fault code?

I was going to go there. That may dent the sales of any sort of jump starting gear to Brisky viewers.

Nice pic, and there's that part number:

It's looking like that part number that I could almost read might be 03L131605AF, the last item 30 listed here: https://skoda.7zap.com/en/cz/octavia/oct/2012-663/1/131-131040/#30 Google imaging that number gives a few piccies of the whole vac pipe set-up which is a scary looking thing. Doesn't help explain its functional role except in so far as it appears on the ETKA page relating to EGR, as @TheClient says. "Probably doesn't work right, or at all, if it's blanked off" might be a good working assumption. Any fault lights? Guess not or you would probably have mentioned it. Would be tempted to leave as is if no faults are apparent; previous owner may have done you a favour.

Christ that's a long and meandering path it takes! 😆

Reflection of camera flash?

Yep.

Yep, that's the main permanent 12V to the fan control unit, but there's an ignition 12V feed too. The diagrams and fuse maps are confusing me to the point of suggesting you check all the blade fuses under that cover to the left of the strip fuses there, and also fuses 8 and 9 in the cabin fuseholder. That should cover all the possibilities I think. Access to the thermoswitch is probably better from under the car, unfortunately. It's in the same vertical line as the top and bottom radiator hose connections to the rad, but rather nearer the bottom one.

It would be fair to say that wasn't a huge success.

I'm suspecting a fuse problem, or wiring fault in the neighbourhood of the fan control unit. Confirmation of which fuses in which fuseboxes you've checked would be good. If you can link out the thermoswitch loom connector that would test the power feeds, the relays in the fan control unit and the power wires to the fan, so ideal really. Don't bother running the engine up to try to trigger the switch, just go straight to unplugging the loom connector from it and linking contacts. There are three wires going to the thermoswitch, a brown, a brown/blue, and a brown/green. To get the low speed to operate, you link the brown to brown/blue; this energises the low speed relay, and should bring the fan on at moderate speed. For high/full speed you link brown to brown/green energising the other relay, but I think the ignition needs to be on for this one to work.

The 'flat rate' isn't shared between the sites unfortunately, I seem to remember. Payments go to different organisations.

OK, so in the middle of that page of the Haynes there are some instructions for testing. did you do 2, 3, or both sections (2 by linking out thermoswitch loom connector, 3 direct wiring to fan)?

Photo would help, but yes, if you still want to bother, you'll probably have to drill it off/out. How many miles on the car? Any specific reason to think it may need changing? Edit: Wait! Why has this been dredged up, it's nearly a year old!

How much did you lower it by?

You only need the cheapest of cheap voltmeters to read such voltages, nothing more technical.

Shouldn't do any harm to anything. Really need to know voltage across battery posts without and with engine running; did you measure those before the car went to the autoelectrician? How many km has the car done, and is it on the factory original battery?

Nothing.

Carefully examine all the pipes coming from the vacuum box, looking for cracks and leaks. Also check for broken wires near the electrical connector to the vac box. Disconnect that connector and check for corrosion on contacts. That's about all I can think of just now. Please let us know if/when you track down the cause. 🙂

No, that's only for engine code ATD, which is the non-vRS 1.9 tdi.