hmmm i would do as follows, erase the codes, unhook the battery for atleast 20 min. (i know this isnt why the code is there, but check your plug wires for touching the headers and also check you plugs to make sure you didnt crack any when you put the headers in.) the hook it back up and see if it throws any codes. could be in the tune as well. when i put my headers on, i didnt throw any codes until plug wires started gettting burnt