Breezy_Pete

Source of the above, https://www.gov.uk/guidance/mot-inspection-manual-for-private-passenger-and-light-commercial-vehicles/8-nuisance#section-8-2-2 Unfortunately there's a sentence even further down the page than what I quoted, referring to retests after fails on emissions at plate figure. Retests must be done at same figure. Has to be said though, there appears to be a lot of variability in how these tests are really done 'at the coal face'.

This is the exact wording of the test manual, for diesels of around this age. I'm not surprised that some testers don't get it right if they skim read straight to "For vehicles first used before..." Before the test, check the maximum smoke level limit for the vehicle and enter the required details into the diesel smoke meter. The maximum smoke level limit will be the level displayed on the manufacturer’s plate; or where there is no manufacturer’s plate information: For vehicles first used before 1 July 2008, the maximum level is: 2.5m-1 for a non-turbocharged engine 3.0m-1 for a turbocharged engine For vehicles first used between 1 July 2008 and 31 December 2013 the maximum level is 1.5m-1 for all engines.

My A4 has a plate figure of 0.7, currently easily legible...

This time they used the plate figure, so 0.8 was what the car had to achieve.

No harm in having a look inside. Find 6 flattish things to get under all 6 clips at once for an easy time disassembling it. Stick some photos up of the circuit board. I'll see if I have a spare.

Ignore that, they are the same for all on RHD pre-facelift by the looks of parts list - 6Q2959802A?

Guess not. Bit rare, the 4 window version unfortunately.

For pre-facelift cars with all four windows electric, the crucial earth to the switchpack is a brown wire that connects pin 11 of the 16-way at the switchpack connector to pin 9 of the black 12-way at the window motor. It's also shown as splicing into an earth wire in the door loom (marked 267 in circuit). Without that none of the switches nor backlighting will work.

Let me just check the circuit in a sec. Did you say you have circuits?

Metal plate in engine bay, or occasionally on B pillar. Has VIN on it too. The smoke value is often in bottom right corner, and it should be in a rectangular box.

Plate value is what they should use 'if it can be read'. The wording in the test manual isn't wonderfully clear though, so the default limit is often mistakenly used. My A4 seems to have been tested to different limits almost in alternation.

If you take the window motor off, the beige cog can be taken off it, put into the door and used to manually lower or raise the glass, perhaps with some pliers to help turn it. Loom repair kits are typically for the single-connector later cars, rather than mk1 Fabia?

Got your message, and will reply in a sec. The answer is yes, driver's side fault does take out all the others, on the LIN-based versions - 6Y1959801/6Y2959802 and 6Q1959801F/G/H/J

@VenomVrs What are you measuring with? Voltage regulators are controlled differently in start/stop cars, and AGM batteries may be charged at higher voltages than conventional ones. Dave is showing max charging voltages per cell for these batteries at different temperatures. Multiply by 6 to get voltage between battery posts.

Yes, make sure the brown wires at both switch pack and lock module are really earthing, but I think the lock one must be OK cos the 'door open' signal relies on it. Backlight in switchpack relies on the same earth as the up/down switches, so do check backlight operation once the daylight goes a bit, later.

How so? The two wires that are black with blue stripe are permanent 12V, the wire that is brown with red stripe is only live when key is in ignition.

https://www.briskoda.net/forums/topic/196288-oem-wiring-loom-colours-pins-for-stereos/

No idea on diagnostics for these systems, nor what readings are to be considered normal range. Could try searching web with your engine code as one search input (DFGA). Part numbers that come up are 04L907807AM, superseded by 04L907807EE for one of them. And 04L907807ES, superseded by 04L907807EG for the other. Both of the current parts retail at £493 + VAT in the UK. @ApertureS probably knows stuff about this system. There will be a Self Study Programme about SCR systems available via erWin, I imagine.

Will look up for you tomorrow.

If you've got a battery charger I'd stick that on it just in case you have taken too much out of it.

Thought so. NOx and smoke (particulates) are completely different things. Not sure I'd spend the money myself, but if you want a part number for the sensor, let me know the VIN.

You didn't disconnect the battery at any point? Loose terminal?

Maybe take the light switch out again and see if there's any sign of a wire getting trapped and damaged? Not going to be easy at night.

On a mk2 Fabia, I would be checking for broken wires in the rubber boot that contains wiring going into the driver's door.