Carpenter joined the then-new Indy Racing League sanctioned Infiniti Pro Series in 2002, driving the No. 2 Sinden Racing car. At the season-opening Kansas 100 at Kansas Speedway, Carpenter started and finished 5th. Carpenter's best finish of 2nd came in the Kentucky 100 at Kentucky Speedway, and he also achieved a pair of 3rd-place finishes in the Michigan 100 at Michigan International Speedway and the Gateway 100 at Gateway International Speedway. Carpenter finished out the season ranked 3rd, with 226 points. In 2003 Carpenter moved to A. J. Foyt Enterprises to drive the No. 14 car. Carpenter won his only Indy Lights race at the series' most prestigious race, the Futaba Freedom 100 at the Indianapolis Motor Speedway. Carpenter qualified on the pole position at the Aventis Racing for Kids 100 at Kansas Speedway and the Chicagoland 100 at Chicagoland Speedway, finishing 2nd in each race. Carpenter again finished the season ranked 3rd, with 377 points. In 2005 Carpenter returned to the series for Vision Racing to drive the No. 9 car on a one-off basis; he competed at the Liberty Challenge on the road course at Indianapolis. Carpenter qualified 13th out of 14 cars and finished 11th, the last car on the lead lap; the result saw him finish 26th in the drivers' championship, with 19 points.