My 2005 Volvo S40 keeps saying low beam failure probably about a month or two now. Sometimes I turn the car on and the light will work and other times it won't. I'm not sure what's wrong with it. I don't want to get a new headlight if that isn't the problem. I'm not sure if it's a wiring problem. I took the headlight compartment out and pulled the wires off the back and plugged it back in and the light was working. I don't know if it's the wire or if it was a coincidence that the light was on. Please help!

 

First question is, when your low beams go out, do both left and right go out together? do the high beams work and can you "flash" the lights from the multifunction stalk?

I'd start simple and replace both low beam bulbs and inspect the sockets/connectors for any signs of corrosion, melting etc. Next time it fails, try wiggling the multifunction stalk, key, dash switch to see if that gets anything to flicker. Next confirm any related fuses are good and consider dropping in a new one.

After that you'd need a tech do do some basic diagnostics where the circuit is opening up. Could be the switch, fuses, CEM, ignition switch, multifunction stalk, bulbs, sockets, ground wires.

Finally if both bulbs are new and go out simultaneously, the reality may be that the issue is internal to the CEM (central electronics module) which on many Volvo models houses relays for the low beams. If those relays fail, the CEM needs to be replaced ($$$$ at the dealer) or repaired. Google shops like Xemodex and Midwest ABS to read up on rebuilding the CEM.