My 08 plate Octavia Elegance has recently seemed to have very dim headlights when driving on unlit country roads, (something I do a lot of ) and I have noticed on a number of occasions when stopped with the engine running that the lights will suddenly appear to flicker and go brighter. The lights don't appear dim when looking at them whilst stationary, but frequently appear to give poor illumination when on unlit roads, this is completely at odds to when I first got the car when passengers would frequently comment on how good the lights were even on dipped beam. The car has done almost 200k miles and is driven predominantly at night; is it possible that the xenons need replacing or is it something else. Does anyone know whether its possible to measure the lights intensity/ brightness

I have heard frequently on other forums that xenons do dim over time. Although they are a bit expensive, but I am sure a new pair of xenon bulbs will sort the problem. 

Put the lights and and stand some distance away and look at the bulbs.

A failing xenon bulb usually shows a pale pink/ weak violet kind of light rather than the typical bluish white.

Xenons will get dimmer over time and at 200k its worth popping in some new D1S bulbs as I certainly noticed a difference when I changed mine at 150k as one them started to flicker.

As others; well that or the dip switch is starting to burn out (less likely with plasma discharge since the switched current is lower).

Thanks to all you guys who responded to my post, it looks like its a new set of xenons for me. Anyone have any idea what they cost nowadays and any recommendations on where to buy them

can recommend hids direct and prices start around £45 per bulb

 

http://www.hids-direct.co.uk/categories/hid-xenon-bulbs/oem-bulbs-by-type/d1s

 

best to avoid ebay as too many fakes knocking around

Thanks wiilydog will check that out

I believe your current bulbs will likely be Osram.

 

Osram are pretty much the go-to brand for xenon bulbs.

 

If you just want like for like then get the standard Osram 4150/4500k.

 

The higher this number the more blue they will be. 4150k will be quite yellowish and the closer to 4500/5000k the better for a bright white light.

 

The cool blue ones @ 5500k will look a bit more BMW/Merc style xenon as I notice they tend to use a bluer light.

 

But here's a comparison: