There is no way to tell you what is wrong by just a code read out. A P2004 code just give you a direction to follow in diagnoses of the problem. You will need a complete computer scan and system diagnoses trace to determine your problem. If you want us to check this out please call 313-562-7022 or schedule an appointment on line at StansGarage.net. I am sure we can diagnose it and give you the answer you need.