Just bought this 2006 S40 T5 AWD a couple days ago, zero mechanical issues, but it has developed an annoying electrical "gremlin" that seems to have gotten progressively worse, and is now pretty much constant.

The "info" light on the dash flashes intermittently (worst during acceleration) and the display shows "Bulb failure warning rear fog light". This is annoying and distracting. It normally stops / the fault clears itself when braking, which means pressing the "OK" button only gets rid of it for a few seconds.

I've checked the bulb and it's working fine (got out of the car, turned on rear fogs, confirmed it's lit) and there's no corrosion or anything on the socket / bulb base, so I don't think it's as simple as replacement. Unfortunately finding the P21/W5 bulb locally has proven impossible. None of my local parts shops stock it, so I'm having to order a replacement online.

The extremely intermittent nature of the fault makes me think it's a short, or break in the circuit -- a wire rubbed through or broken somewhere -- but I don't look forward to tracing for the problem. With that in mind, I'm asking around first -- I've seen this mentioned as a common or at least known problem with this year/series of car, but it's always "oh yeah that's a thing sometimes" with no suggestion of a fix.

Has anyone here dealt with this issue before, and how did you resolve it?

Thanks!

 

Pulling and re-connecting the bulb and attached assembly a few times seems to have cleared the fault for now (again, no visible corrosion anywhere) but I doubt this is a long term solution. Guess we'll see.

 

Good work - that's just what I was going to recommend - I'm betting that if you would have tapped the rear light with it on "pre-fix", it would have gone on and off. I think there's every chance that it's "fixed" - could have been just a slightly funky connection between the bulb and the socket pads that got cleaned up when you removed / re-installed the bulb.

 

Hopefully you're right. Next project? Pull the driver's side door wiring connection and go to town with deoxit and dielectric grease, in hopes of fixing the "it's always under 40 F outside" thing.