The contact owns a 2015 Kia Soul. The contact stated that the front passengers seat belt failed to latch and lock securely. The rear middle seat belt was difficult to close. The contact stated that the check engine warning light was illuminated. The vehicle was taken to the local dealer where it was diagnosed and determined that the oxygen sensor and catalytic converter were replaced; however, the failure recurred. The vehicle was taken to an independent mechanic who referred the contact to the dealer. The manufacturer was contacted, and informed the contact that a diagnostic test was needed. The failure mileage was 104,000.