Kenseth also was docked 50 championship points, and the 2003 Cup champion then saw a strong Daytona finish vanish on the last lap in a multi-car crash.
But Kenseth put Daytona firmly behind him yesterday by keeping his Ford Fusion ahead of five Chevrolets and winning the Auto Club 500 for the second consecutive year at California Speedway.
The victory, the 15th of Kenseth's career, completed a weekend sweep in Fontana for the Wisconsin driver and what is now Roush Fenway Racing. Kenseth also won the Stater Bros. 300 Busch Series race Saturday night.
"The car was really good all day," said Kenseth, who also led the most laps with 133.
For a while, it appeared that Kenseth's biggest threat would be another Chevy driver, Daytona 500 winner Kevin Harvick, who was closing fast on Kenseth in the final laps until an accident involving David Reutimann and Bobby Labonte set up the last restart.
Just as the field was preparing to take the green flag, Harvick's car suffered a flat left front tire, forcing him to pit. The Bakersfield, Calif., native finished 17th.
"It has been one of those weeks," Harvick said. "A flat tire yesterday in the Busch race and a flat tire today."
But Gordon, who started on the pole, said he wasn't sure Harvick or anyone else could have caught Kenseth.
"We really never had anything at the end for Matt," said Gordon, the fastest qualifier and the only three-time Cup winner at California Speedway, where no driver has ever won a Cup race from the pole.
Harvick edged Martin a week earlier to win the Daytona 500, but their finishes yesterday gave Martin the early lead in this year's championship battle.
Martin has 335 points, followed by Burton at 330 and Gordon at 309. The last time Martin, 48, led the series was in mid-2002.
Kenseth arrived in Fontana without his crew chief, Robbie Reiser, after Reiser and four other crew chiefs were suspended by NASCAR for cheating during qualifying for the Daytona 500.
Roush Fenway is appealing, but Chip Bolin served as Kenseth's interim crew chief.
Kenseth's victory also was the first win for Roush Fenway, formed earlier this month when a group led by John Henry, principal owner of the Boston Red Sox, acquired half of Roush Racing.
But Stewart made a costly mistake - he sped down pit road and was penalized - which forced him to the rear of the field. He rallied to finish eighth, but the 2002 and 2005 Cup champion still has never won at California Speedway.
Jim Peltz writes for the Los Angeles Times.