what cause the engine light to show on

Take your car to a local autoparts store such as AutoZone or Advance Autoparts and they will scan the car's computer via the OBDII(OnBoard Diagnostic) port for free and tell you what the problem is.

I have a Volvo s40 2.4i 2009 and the check engine is in, but have no messages, I have two situations, the first is the serpentine belt is a little ripped and cause a little squeak, you think so that's cause a check engine light take on, and the second, I see a pipe from intercooler open, the piece is probably broken, but is out there of intercooler filter, probably that comes on the check engine light.?