Hi all.

 

Have a 2006 Diesel Octavia with a bulb warning light in the dashboard.

 

It's one of the rear bulbs, and when I check it, there is a faint light on the filament.

 

I got a new bulb and tried it, but it was the same faint light. The equivalent bulb on the other side is fully lit.

 

Any suggestions?

It is most likely a poor connection with these possibilities:

- corrosion at the contacts in the bulb holder

- if it is a double filament bulb it has been put in the wrong way round

- a poor supply or earth connection at the bulb holder

- a poor earth connection where the earth wire joins the earth stud in the left hand side of the boot

- general corrosion of earth wire and stud in the boot caused by water or (more likely) rear screen wash liquid.

[Note that if the rear screen wash has a low concentration then in winter it can freeze and push open the pipe connection]

 

If you have a multimeter you can check all connections one by one.

On my Octavia, my rear fog light is like that when turned off in the photo however when I turn it on, it illuminates like a normal bulb.

It seems odd that you're getting an error, maybe try resetting the code using an OBD reader?

Not sure if this helps but these cars use a slightly unusual twin filament bulb. It's a type 566 and is 21w/4w. If you put a more conventional 21w/5w one in it will work but the warning light stays on. 

Thanks for all the suggestions. I took the bulb housing from the other side and connected it to the problematic side. The top bulb worked no problem. Which I'm guessing means it's the bulb housing indeed to replace, possibly due to connection issues like Pikpilot mentioned.

 

I also tried to clear the error using VCDS. The error came back straight away.

You have the wrong double filament bulb or it is incorrectly inserted although you would have to try hard to do that, your conclusion from trying the other bulb housing is illogical, it would have been more revealing to have swopped the rogue bulb with the one from the other side.

48 minutes ago, J.R. said:

You have the wrong double filament bulb or it is incorrectly inserted although you would have to try hard to do that, your conclusion from trying the other bulb housing is illogical, it would have been more revealing to have swopped the rogue bulb with the one from the other side.

Hi.

 

I swapped the bulb first. With the "new" bulb that was swapped over, it didn't function properly in the "rogue" location. I switched it back to the other side and it worked fine.

 

Can you expand on why you think the idea that it's the holder is incorrect?

 

I've swapped bulbs, and the problem stays in the same spot. 

 

Moving the holder and demonstrating that the good one works on the rogue side would suggest the wiring is ok leading to the holder.

 

This leads me to conclusion that the problem is somewhere between the bulb and holder connectors.

 

Can you let me know where my logic fails?

Your logic is sound, I had not appreciated that you had swapped the bulbs, I probably did not read carefully enough, I only dip in and out in the odd 5 minute break.

 

Apologies!

38 minutes ago, J.R. said:

Your logic is sound, I had not appreciated that you had swapped the bulbs, I probably did not read carefully enough, I only dip in and out in the odd 5 minute break.

 

Apologies!

No problem. Maybe I didn't state it clearly anyways. The joys of communicating on forums!

 

Thanks for confirming I'm not crazy 🙈