CEL Is the Check Engine Light, also referred to as a SES (Service Engine Soon) or MIL (Malfuncion Indicator Lamp). It shows up as a light on the dash that looks like a little motor. It lights up when there are trouble codes stored in the vehicles PCM (Powertrain Control Module). You can check the codes by turning the key on-off-on-off-on, or Autozone and most part places will scan for codes for you. Ask if you have any more questions, hope this helped man!
Best of luck,