The #99 Nissan was found to be in breach of Rule C8.1.4, which stipulates the compulsory scrutineering seal for the cylinder heads, sump and rocker/cam covers.
Moffat has subsequently been disqualified from both of the Saturday qualifying and races.
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A Nissan Motorsport spokesman told Speedcafe.com that the issue was the result of an oversight from the team.
“We applied to V8 Supercars to remove the seals on Friday to do some work on the engine and were approved to do so,” the spokesman told Speedcafe.com.
“Then out of error the technical person (from our team) didn't advise V8 Supercars to have the seals replaced.
“Our team picked it up this morning and advised V8 Supercars that this was the occurrence, after which the minimum penalty was applied.
“From our side we are extremely disappointed for James that he has copped the brunt of the issue when it was an internal person that had the oversight.”
The 31-year-old had started seventh and finished eighth in the first heat before holding a 13th grid position to the flag in the second.
The disqualification sees Moffat lose 78 points, dropping him from 15th to 17th in the standings.
Moffat recovered from a poor start to finish 10th in today's finale race of the weekend.
Rule C8.1.4 in full
“Each engine must have suitable provision for the cylinder heads, sump and rocker/cam covers to be sealed to the cylinder block so that the cylinder heads, sump and rocker/cam covers are not able to be removed.
“It is the Team's responsibility to ensure any engine installed in a Car is sealed prior to the commencement of qualifying at any Meeting.
“Once an engine has been sealed, the seals must remain intact and legible at all times.
“These seals must only be removed by the S&TD (Sporting & Technical Director) or with the express prior approval of, and subject to the conditions of, the S&TD.”