Breezy_Pete

The fuse supplies one side of the heater in each sensor, the other wire of each heater, and the two main sensing wires from each all go to the engine ECU.

No worries, but do look back at my edit to previous post. Might be a handy precaution.

Yeah, no problem to drive, especially if you don't fill it up so much that you (mis)trigger the low fuel warnings. Carry a spare 5L can in the boot though, for when you forget it's backwards and run out.

Well that page claims equivalence with both the numbers I've suggested, and more, but the skoda-parts.com pages I linked for you do not suggest that the two are equivalent. Those pages specifically mention different applicability (pre- and post-face-lift cars), so I think you've fallen victim to over-generalisation by Autodoc. PITA if you have to try to return to Berlin. The pumps are usually very reliable, I'd go 2nd hand off ebay if it were me.

Was just looking at part numbers now, for the petrol engines, 6Q0919051 suits pre-facelift cars like yours, 6Q0919051F suits cars from MY2005 onwards as far as I can see from these two pages: Fuel Pump China 6Q0919051 (skoda-parts.com) Fuel Pump Bosch 6Q0919051F (skoda-parts.com) What does the Autodoc part you bought claim as equivalent OEM part number?

Places like Autodoc and ECP often get such things wrong. Next time I get up I'll have a look at (genuine) part numbers and when the change was. Do you still have the old pump, and why did you replace it?

Was the replacement pump secondhand? At some time in the mk1 history they changed the way the fuel gauge sender works. Sounds like you may have a mismatch.

Can you clear the error codes? How many times have you driven the car since refitting the fuse?

@TheBlackDog If I were you I would take off each end of the chassis to engine earth cable, and clean thoroughly with very fine wet-and-dry lubed with WD40 or similar, or a fine wire brush. Cleaning without removing will do almost nothing. Alternator voltage regulators have a pronounced temperature dependence, which may account for some of the variance in readings that you are seeing. Approx -0.005V/°C from memory, so somewhere approaching half a volt higher when stone cold in winter compared to fully warmed up/heatsoaked alternator isn't unexpected.

Absolute pleasure, thanks for the shout out. Thanks @varooom for drawing my attention to it.

With an assistant to turn and hold the key in cranking position, measure for 12V at the connector of the 'wire of doom'.

Yep. Copper wiring is very ductile, so should stretch for a long way before it breaks in tension.

Brown is generally an earth, black usually an ignition switched 12V. I'd just be pulling (firmly) all the other ones emerging from there, hoping that will bring the brown out. Wherabouts in the UK are you?

Maybe keep the other switch for summer when ambient temps are higher and the delta may be rather less. 🙂

Front or rear? And which exact bulb have you replaced them with, I seem to remember they are a slightly unusual fitment with offset pins. PY21W is the correct one (unless you're talking about the side repeaters)

Only thing possibly worth mentioning is that the fans can suffer a failure mode that leaves them as 'unreliable starters'. There are two sets of brushes orthogonal to each other, and it can happen that one pair, or one brush of a pair, gets stuck in its holder and no longer reaches the commutator. In a how-to of fixing the low-speed resistor failure of these fans, the author unintentionally illustrates this by posting a photo of his fan's innards with two telltale, stuck back brushes, one from each pair (top two in image): http://i4.photobucket.com/albums/y146/Imagewerx/Fan%20resistor%20fix/018_zpsdf767ee1.jpg This sort of partial failure may result in "sometimes it starts, sometimes it doesn't" behaviour. I think a supersedence of the fan part number for the single-fan version like yours is still used in some considerably younger cars, so ebay may have some reasonably priced second-hand genuine units. I bought one a year or two back for something like £30 delivered, which seemed good value for a genuine item that was I think maybe ten years old rather than 18 or whatever. I never installed it, as it happens, 6R0 959 455 E, I think, e.g. SEAT Ibiza 6J 2016 TSi Petrol model ENGINE COOLING FAN MOTOR and COWLING SHROUD | eBay

https://m.youtube.com/watch?v=7QTS3SD-iCA

The last of those codes points to an issue with the wiring to the N280 valve, I think. Reddish-brown two-way connector pair on the bracket near starter motor is typical wiring trouble area. It's a bit odd, as you say, if it wasn't working at all you wouldn't expect the rev/load compensation. 95k isn't particularly high mileage, so I doubt the water pump has had it.

I doubt your compressor clutch kicks in, because there isn't one. Your car has a variable displacement compressor controlled by a solenoid valve, N280. It's always pumping a little, even when A/C is switched off. Share the hvac fault codes for more suggestions. The radiator thermoswitches are not usually a failure point (other than coolant leakage), as they only carry relay coil currents, not fan motor currents, in this set-up. I wonder if coolant flow through radiator is low? How many miles on the clock? See how things settle down with new thermostat etc. 🙂

Is your 1.4 a BXW engine code? If so, then yes, fuse 31 should be a 10A fuse feeding the heater circuit of both oxygen sensors.

Do EU6 engine codes start with D instead of C?

Found a list in a post by bluey here: https://www.vwwatercooled.com.au/forums/f40/volkswagen-under-investigation-over-illegal-software-masks-pollution-108532-9.html

I think yours will be an EA189? What year?

LEDs can be far more reliable, but aftermarket automotive ones are extremely variable in quality. Loads of posts on here about multiple failures in people determined to mess about with suchlike.

No drums on a vRS @VWD.