Breezy_Pete

Which engine type?

Yep. Are you changing the relay, or the whole unit?

Indeed, also mentioned in that link above; Skoda refer to it as "Control system for exhaust gases" Screenshot from a mk2 Fabia Owners Manual:

Electronic Power Control, I think. And MIL is Malfunction Indicator Lamp. EPC is spelled out in capital letters on cars with that warning light. Here's a post with an extract from an owners manual: https://www.briskoda.net/forums/topic/150495-epc-warning-light/?do=findComment&comment=1874575

You might find it's got a failed low-speed function, so worth checking that out. Very common failure, I believe.

Could be a very long time, especially if your car has a diesel engine; much better to go out for a drive, preferably a lively one, then leave the car idling afterwards to observe such fan action. Take a litre or so of top-up coolant with you in case the level drops enough to trigger the low level alarm whilst on the road.

You're possibly better off asking for help in the appropriate subforum on here, to be honest. The official manuals are not that nicely written, although they do cover absolutely everything, but in many different documents. I wouldn't have a clue where to start to look for answers to your 'for example' issue above, but someone on here probably will have some good suggestions, and may even have had and solved that exact problem.

Just use the workshop manuals.com site then; same info, just without working hyperlinks etc. and with a generous supply of pop-ups. Why would you need to keep returning to erWin if you've downloaded the pdfs?

Offical Skoda manuals site? - Handy Topics & Guides - BRISKODA

Not at all. It is copied directly from info on official sources such as erWin Skoda though, within which a small fee for an hour's access unlocks a vast database of downloadable pdfs if you go via the individual vehicle information tab.

I should think it was probably just a typing error on the invoice? How much was this part? If you're a very lucky person, it may have been installed with the part number facing in a direction where it can be seen unobstructed by too much other stuff..

So my engine isn't lean burn after all? Let's see what the OP finds out, and perhaps Stewart, rather than blether on irrelevantly about other stuff.

I was just pointing out the oddness of sepulchrave's comment about 'lean burn' engine in my car.

stoichiometry - Google Search

Both run at stoic due to lambda control and cat(s).

Have you looked at the sensor output on yours with VCDS or similar Stewart, to see what temperature it runs at? I wouldn't be at all happy if my engine ran at 80C.

Apart from making it more difficult to remove the panels that leak by changing the fasteners from screws to rivets in 2004!

Thanks for adding to this @xyzal. Shortening and refitting with heat may work if the hose is long enough. On the BBY-code engine in my Polo it isn't, sadly. I've temporarily patched it with self-amalgamating tape and a couple of tyraps, but it will have to be changed again at some point I think.

Subject being brake servo vacuum hoses. Not sure quite how universal this failure is, but I've seen so many now on friends and neighbours' cars I always check them any time I remember to whilst under the bonnet of a Volkswagen Group car. The hard plastic sections split where they are stretched over the barbs of hose nipples on the terminations at e.g. the non-return valve. If the hose completely parts company with the bit it's attached to you will lose all servo assistance for the brakes. The brakes still work, but you have to press a hell of a lot harder on the pedal. If you don't know this, you will believe the brakes have failed completely. Before this catastrophic failure, if the splits develop to the point of leaking significant quantities of air, all sorts of weird fault codes can be thrown up, leading to replacement of non-faulty parts if diligent diagnostic techniques aren't used. Lambda sensors, throttle bodies, all sorts of things could get the blame due to 'false air' entering the intake manifold through these splits. The splits I've just found were not super-obvious. The first one on the underside, I felt with a fingertip before bringing a mirror out to inspect it. The second split, and worse one was on the front side, facing the engine, and couldn't be seen or felt easily until I pulled the whole assembly out a little to inspect more carefully. How old was this hose assembly on my car? 5 years only. The original was found in a similar or worse state about that long ago, this was a new genuine replacement then. Guess what improvements have been made in materials and design of these hoses since this car was made in 2003? None whatsoever that I can see. Please check your own car's equivalent. Go on, you have some time in the next few days, right? If you find crap like I just did, please photograph it and add to this thread.

It worked again, just. Sounded even less likely to start than the previous time, but it did. It is unseasonably mild today though.

No, a day later. Did run the engine for half an hour after, as I do approx. monthly on this vehicle whilst it's off the road. Out of curiosity I'll go and try it again now. Has been disconnected from the car in the meantime.

Update on that battery: charged it for several days at 13.8V on a bench PSU. Put it in my spare Polo to see if/how it worked, and it started the engine, but only just. Unsurprising, at 15 years old.

Did the new thermostat housing come with a new temperature sensor, or did you move the original sensor into the new housing?

I'm not near my computer to look for good photos/videos just now, but search for "vw connector removal" on YouTube and you should find a few useful results. In words; push the connector body firmly onto the thing its plugged into while lifting the latch up a short distance in the opposite direction until you hear a click. Then pull connector away Find an easily accessible one to practise with. If you don't do that initial pushing, friction on the latch parts may cause breakage.

@drifter1949 are you familiar/well practiced at undoing the latches on these type of connectors? There's a 'knack' to it that's not completely obvious.