You need to put a scan tool on your car to find out what error code your car is putting out.
Any good mechanic with have one or do it yourself for cheap. It's like having an onboard computer.
http://www.ebay.com/itm/WIRELESS-BLUETOOTH-OBD-2-OBD2-ODB-II-INTERFACE-SCANTOOL-/110686061333?pt=Motors_Automotive_Tools&hash=item19c5674315&vxp=mtr
Get one of these with an Andriod phone. It will tell you everything about your car as you drive.
Very cool on a tablet.
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