Method for determining pressure at the outlet of an exhaust gas system

The method involves detecting a mass flow through a combustion engine system (1), and sensing an ambient pressure at a fresh air supply (8) of the combustion engine system. The pressure at the outlet of the exhaust system (6) is determined corresponding to the mass flow, the ambient pressure and a throttling of the mass flow through the combustion engine system. An independent claim is also included for a combustion engine system for a vehicle, which comprises a detection unit for detecting a mass flow through the combustion engine system.