C5 fog lights

[PC2CV]

I have a minor defect on my c5s mot fail sheet, the rear fog lights. The tester said he couldn't see them on.

I plugged Lexia in they do come on on one of the filaments of the bulb, the same bulb is also doing the rear tail lights. It's just very hard to see any discernable difference with both filaments lit up. I have fitted a 21/4 bulb as per the owner's handbook, has anyone ever found this to be an issue with the MK1 C5?

[Clogzz]

The rear fog lights will only light up when the headlights are on, and after the fog lamp switch has been flicked twice; to turn on the front fog lights first, and then next the rear fog lights.

[PC2CV]

I dont have front fogs on this C5, the rear filament lights up its just you cant really see a huge difference standing behind the car.

[GiveMeABreak]

Have the bulbs been changed for a non-standard aftermarket 'upgrade'? If the bulb is any colour other than clear, the rear lens will reduce filter out and reduce the light seen. Either that or the rear lens might need cleaning - it could be filled with spider webs or other crud as the seals can let in bugs over the years.

I would also double check the bulb type - as per the manual it should be a P21/4W as you say - however a LOT of on-line retailers have the complete wrong set of bulbs for Citroen - they are entirely hopeless. If you look at a lot of the on-line UK retailers, they simple list a P21W bulb for the rear fog - which is rubbish and is a single filament - so would not provide any light if the fogs were switched on.

This is the correct bulb - but you won't find it using their on line car lookup - you need to locate it manually:

http://www.halfords.com/motoring/bulbs- ... -bulbs-x-2

Always worth checking you do have a P21/4W in there.

[PC2CV]

In the end, i went to my local filling station they stock ring bulbs and tried their 21/4w, the ones I put in were from my local motor factors and at 50p a piece they were the problem, the new ring bulbs are working fine.

[GiveMeABreak]

Result