The probation was punishment for the two intentionally bumping each other after the conclusion of last Saturday's race at Phoenix International Raceway.
The two drivers made contact with 11 laps to go, causing Earnhardt to crash. Earnhardt then spun Mears on the cool-down lap. Mears retaliated, bumping Earnhardt on pit road.
NASCAR stated that Earnhardt and Mears violated Section 12-4-A (actions detrimental to stock car racing; hitting another competitor's car after the race had concluded) of the sanctioning body's current rule book.
The probation takes effect with this race weekend at Talladega Superspeedway and concludes after the May 31 race at Dover International Speedway.