NASCAR took William Byron's #24 and Alex Bowman's #48 cars back to the R&D Centre after the Richmond round for what it called “further inspection”.
The teams were found to have made illegal modifications to the greenhouse of both cars.
The #24 and #48 teams have each been docked 60 driver and owner points, as well as five playoff points. Interim crew chiefs Brian Campe and Greg Ives have been suspended for the next two races and each fined $75,000 as well.
The points penalty drops Bowman from the lead of the regular season standings down to seventh, while Byron drops from fourth to 14th.
Hendrick Motorsports finished 1-2 in the race, with Kyle Larson beating team-mate Josh Berry, while Larson's #5 car passed post-race inspection without issue.
Second offense
This is now the second time during the 2023 season that NASCAR has found the Hendrick organisation to be in violation of the rules.
On 15 March, NASCAR penalised all four Hendrick teams for the modification of single-source supplied parts, specifically the hood louvers.
Along with $100,000 fine and four-week crew chief suspension for each team, they were all docked 100 driver and owner points and 10 playoff points.
Last week, although an appeals panel found the team guilty, they still rescinded all points penalties against them, as they found the suspensions and monetary fines to be sufficient.
Hendrick Motorsports has released the following statement in response to the latest penalties: "We are reviewing the penalties issued today by NASCAR and will determine next steps following Sunday’s race at Bristol Motor Speedway."
