Speedcafe.com has learned that stewards are looking into the matter as to whether it influenced the outcome of Sunday's race.
Coulthard dramatically slowed under the Lap 135 Safety Car, backing up the pack behind the #12 Ford Mustang while the lead two of Jamie Whincup and eventual race winner Scott McLaughlin, in the sister #17 Shell V-Power Racing Mustang, scampered away before electing to dive into the pits.
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While McLaughlin and race leader Jamie Whincup continued to the pits at speed, Coulthard slowed so much that he was well over 40 seconds slower than his team-mate on that lap.
As such, he avoided stacking behind the #17 Mustang in the DJR Team Penske pit bay, but was subsequently issued a drive-through penalty for breach of Safety Car procedures.
Speaking to media post-race, Coulthard explained that he was instructed by the team to take extreme caution due to an overheating engine.
It is unclear what sanctions the Confederation of Australian Motor Sport could impose on the team if found guilty of a rule breach.