It has been revealed that, in November 2020, Porsche issued a stop-sale for certain models equipped with its Sport Chrono Package.

The German car manufacturer never publicized the stop-sale and the U.S. National Highway Traffic Safety Administration (NHTSA) wouldn’t comment on the issue. However, a bit of digging from Business Insider has uncovered what is going on.

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Porsche has indeed ordered its dealers to stop selling certain used models equipped with the Sport Chrono package. The reason is that internal testing has revealed that when the affected vehicles are driven in ‘Sport Plus’ mode, they emit more nitrogen oxide than permitted.

“Porsche proactively informed authorities and continues to work to review the issue,” a Porsche spokesperson said. “Both the ‘Normal’ and ‘Sport’ modes were found to be compliant with all known emissions standards based on testing performed by the company,” but, apparently, there are issues with Sport Plus. “In any case, we have no indications that cars currently in production are affected.”

Business Insider notes that the stop-sale impacts 911, Boxster, Cayman, Cayenne, and Panamera models from the 2012-2016 model years. Porsche is still in the process of investigating which specific variants of each model are impacted by the issue, stating that it is being “cautious” and “testing every model derivative.”

“I can understand why some of your readers would be concerned,” the spokesperson continued. “To be clear, our dealer partners are buying all used Porsche cars as they usually would, and the cars in customers’ possession remain safe to drive. What the dealers have paused is selling the specific cars in their inventory affected by this until the software on these cars can be updated.”

Porsche has not said when it expects the necessary updates to be completed, but assured owners that it is not a safety issue.