Lowndes was fined $15,000 yesterday for irate comments he made after twin penalties at the Indy meeting last month.
He had seen a 101-point championship lead reduced to just 30 after Indy and responded unwisely to reporters' questions about the stewards' penalties.
Lowndes left open the interpretation that the stewards' decisions had had the effect of ensuring a close finish in this year's championship.
While he clarified his statements the next day, saying he never meant stewards were trying to manipulate the championship, he was charged with bringing the sport into disrepute.
After an initial hearing last week before the sport's prosecuting officer, Peter Wollerman, Lowndes decided to fight the charge.
However yesterday, with a further points penalty possible, Lowndes changed his mind and pleaded guilty.
He repeated the clarification of his comments but this time the statement also came with a full-blown apology.
"I recognise some of the comments I made were inappropriate and I therefore apologise unreservedly to the stewards and officials for any offence I caused," he said.
Of the total $15,000 fine, $5000 was suspended and with no points penalty Lowndes takes his lead into the Tasmanian round of the championship this weekend.
The races at Launceston, ahead of the international round in Bahrain and the season-ending Phillip Island round, will decide this year's V8 Supercar champion.
Lowndes' main rival is Holden driver Rick Kelly although Ford driver Mark Winterbottom also harbours some aspirations from third place.