PPI is available on personal loans and credit cards to assist people in repaying their debt if they fall ill or find themselves unemployed.
However, the OFT is investigating whether providers are making excessive profits on the service, following complaints by Citizens Advice last year that PPI is too expensive and does not always cover some of the most common problems such inability to work because of back problems.
Shane Craig, managing director of Payment Care, said last week: "Whenever you have a secondary product that's generating more profit than the primary product, the system has broken down."
Some money lenders offer secondary products such as PPI to try to make up for low interest rates and, as a result, it is frequently sold to people who have no need for it.
PPI can be useful for some people but consumers are advised to check the full cost of the product before signing up, to avoid paying above the odds for a service that they do not need.