Many car parts stores have the equipment to pull the codes from your system for under $100. They are easy to operate and also supply a book listing the trouble codes and their meaning. Some stores will provide the service for free in turn for purchasing the parts from them to correct the problem.
With a scan tool
FORD 2004 S.N.M014617 FORD 2004 S.N.M014617 FORD 2004 S.N.M014617
Check the fuse?
You can find a diagram of the fuel system for a 2004 Cavalier in the car's owner's manual. You can also check with local auto stores.
if engine runs fine but computer has [large] emissions leak , check too see if gas cap is on all the way or missing,
Trouble code P0700 means: Automatic Transmission Control System Malfunction You need to check the TCM for codes.
Check the fluid, check for codes.
If you have a bad O2 sensor the check engine light would come on and set a code directing you to which one is bad. A code reading tool would be required to read the codes.
Auto Zone will check your computer codes for FREE. Have codes check and go from there.
The error codes indicate a failure has been detected. If you ask a question with the specific code number, with year, model, and engine we will try to answer.
Check
how do you replace thermostat for 2004 cavalier