I would start with replacing the spark plugs. Should be around $20 for the set. Disconnect the battery to re-set the check engine light. If that doesn't take care of your problem and you get the light again, go to Autozone and get the coil that mounts on the #2 cylinder plug. You have two coils, on #2 and #4. Cylinder #1 jumpers to #4 and #2 and #3 are jumpered together. It is real easy, just disconnect the molded plug that runs to the coil, remove two bolts and remove the plug wire that goes to #3 cylinder. Hope that this helps.
The 2004 Kia Optima has 16 valves.
The 2004 Kia Optima has a 5-speed manual.
The 2004 Kia Optima has an inline 4 engine.
The 2004 Kia Optima is a gas-powered vehicle.
you have two left/rights
4 cylinder 2.4 litters uses 10W40
which engine 4cylinder yes 4 cylinder
The 2004 Kia Optima has double overhead cam (DOHC).
The 2004 Kia Optima runs on regular unleaded.
The height of the 2004 Kia Optima is 4 ft. 7.5 in. (55.5 in.).
The 2004 Kia Optima is 15 ft. 5.8 in. (185.8 in.) long.
The 2004 Kia Optima's turning circle is 34.1 ft..