check engine light came on

ASSISTANCE Hybrids & Advanced Aftermarket Engine Performance
1

so i installed my dc 2 piece header…start it up…checked for air leaks…and all seemed good…drove it around the block and all seemed good…i hop on the freeway get on it a little bit and the check engine light came on…any ideas on what it could be? hope its nothing too bad

2

Check what code the CEL is throwing.

3

o2 sensor