Finally a nice easy little job! Turns out the OEM S4 Xenon headlights are a simple (almost) plug and play upgrade, even if coming from regular A4 halogens.
The plugs/connectors are the same, no VCDS coding required, no wiring. Just four torx bolts (T30) for each light, slide the old lights out, replace with the new ones and plug them in.
OEM Valeo ballast on underside of one of the S4 units…
I’d joey’d my original headlights anyway and had fitted aftermarket HIDs, so these S4 units are pretty similar to what I had before. It’s just nice to be OEM and not worry about radio interference or dash warning lights for ABS and traction that the HID kits are prone to suffer from.
Update [18.03.2014]: They’re not quite ‘plug and play’!
I only discovered very recently that my beam level adjuster wasn’t having any effect when turning the little knob on the dash. This appears to be the only thing that isn’t ‘plug and play’ and will require an adapter or a bit of clever re-wiring.
The problem is because the OEM Xenons are designed to be auto-levelled rather than manually adjusted, the servos that take care of the adjustment (I’ve heard) are expecting an additional input.
I had seen Kufatec did some adapters, but theses are for the super rare bi-xenon units, and won’t get the regular S4 xenon levellers working.
The adapters are available as a pair from Kufatec, here’s the link: http://www.kufatec.co.uk/shop/index.php?page=product&info=677
It is technically possible to swap the levelling motors from a manual-levelled cluster and retrofit this into the xenon unit, replacing the auto-level motor. If I get around to doing this I’ll put together a how-to guide.
I’ll need the adjustment working before MOT time as if the beam pattern is out when tested, and they can’t adjust it I imagine that’ll be a fail. Fortunately the pattern is at a reasonable height at the moment so I’m not in any rush to swap the motors over just yet.
I know retrofitting the complete auto-level system is possible but I don’t think this is something I can be bothered to look into right now.