The #11 Ford Mustang finished the race in 21st position, directly behind the #9 Erebus Chevrolet Camaro of fellow rookie Jobe Stewart.
Stewart, though, was relegated to last due to a five-second time penalty for a bump-and-run move on Walls at Turn 2 on lap 13 of the race.
A stewards report revealed that Walls made contact with the rear of Stewart’s car between Turns 3 and 4 on the cool down lap.
The incident was deemed by stewards to be careless driving, with Walls having no explanation as to why the contact had occurred.
“The Stewards summoned and heard from the Drivers of Cars 9 and 11 and their Authorised Representatives and reviewed broadcast footage,” read the report.
“The footage showed Car 11 gaining on Car 9 on the cool down lap and making slight contact with the rear bumper of Car 9 on the approach to Turn 4.
“The Driver of Car 11 said he was not sure why it had occurred but immediately regretted it.
“Having considered the matter, the Stewards determined that the contact with Car 9 was unnecessary and inappropriate.
“The Driver of Car 11 is reprimanded.”
The two drivers again took the chequered flag line astern in the day’s second race, this time with Walls 21st and Stewart 22nd.
This article first appeared on Speedcafe.com, a sister site to MotorRacing.com.