The contact owns a 2017 Subaru Forester. The contact stated that while the vehicle was being started, the contact heard an abnormally loud sound coming from the engine. The contact stated that a dealer was contacted. The vehicle was taken to a dealer where it was diagnosed and determined that the catalytic converter needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The manufacturer referred the contact to the NHTSA Hotline to report the failure. The approximate failure mileage was 156,774.