Certified pre-owned sales have declined, falling over 11% year-over-year in September and off 5% since August, finds a Cox Automotive analysis of Motor Intelligence data.

September saw 201,707 CPO vehicle sales, the softest number in seven months. Year-to-date certified sales sit at 1.84 million, down 15% from 2.16 million in the first three quarters of 2021, Cox reported.

 “The one upgrade in our quarterly forecasting updates for Q3 was to take CPO sales up slightly,” said Chris Frey, senior manager of economic and industry insights at Cox Automotive, in a news release.

“CPO has been up and down this year as it’s impacted by supply and demand, but we should see CPO end the year at 2.4 million,” Frey said. “The value of an extended warranty cannot be understated, especially in a rising cost environment.”

Still, Cox data shows that 2.4 million figure represents a 12% year-over-year decline and far less than the 2.8 million CPO vehicles sold in 2019.

Cox data shows 619,662 certified sales in the third quarter, down from 699,809 CPO sales in Q3 of 2021.

Not all automakers are seeing falling CPO sales. For instance, Mercedes-Benz — after reporting its second strongest first-half CPO sales ever — posted 33,624 certified sales in the third quarter, beating second-quarter sales by 1.6%. Mercedes has moved 99,652 certified vehicles year to date.