A 27-year-old Onkaparinga Hills woman has been sentenced to community service after selling a second-hand car with an odometer that had been wound back.

The Adelaide Magistrates Court was told Jessica Jane Seiboth bought a second-hand Mazda CX-9 from a Morphett Vale dealer for $19,990.

At the time, the odometer reading was approximately 129,140 kilometres.

A few months later, she sold the car to a dealer in Mile End, with the odometer wound back to approximately 77,00 kilometres for $19,000.

This was well above the amount the dealer would have paid had the mileage been accurate.

Consumer and Business Services investigated the matter after the dealer and the Motor Trades Association lodged a complaint.

The Court was told that Seiboth was bankrupt, and had failed to provide authorities with any details on who was responsible for tampering with the odometer.

In sentencing, Magistrate Christopher Smolicz noted Seiboth was not a person of means, and that her offending was 'foolish', saying she made little profit from it.

He recorded a conviction and sentenced her to 168 hours of community service.