Consumers who are looking to buy a used car say that they often check a vehicle’s history by using a report from companies like Carfax or AutoCheck.

But consumer advocates say that those reports may not always be accurate or tell the whole story.

“Carfax gets information from more than 100,000 sources,” says Carfax spokesperson Christopher Basso. “With accidents, it can come from police department, body and repair shops, a number of different sources.”

But because these companies rely on outside sources, Carfax and AutoCheck make a point to say that they are not responsible for any information that may be wrong or missing.

Some common reasons that accidents might not show up on a report include: 

Consumer experts say that when buying a used car, it may be worth it to get a vehicle’s history report from more than one company. 

A buyer may always want to have a mechanic check out the car as well. They may notice damage that is not on the report.