well.. i put a prong into the jumper wire and my codes wont come up! how can i check my codes.. i also took it to a mechanic and he tried to jump it from the ecu.. still nothing.. i was throwing codes with my p13 before and he couldn't check it.. so now i'm running a chipped p28 and the car is running better... but once in a while it'll throw a code... why can't i check my codes? any help will be very helpful. thank you.

 

If the CEL just stays on and doesn't flash a code, that means that your ECU isn't getting power. Check all the wiring back to the fuse box, check your fuses, you should find something wrong there.