Method and device for diagnosing an air supply of an internal combustion engine

An internal combustion engine system comprising:

• an internal combustion engine including:
• a cylinder;
• an exhaust gas system;
• a heater;
• a first air duct configured to supply air to the cylinder;
• and
• a second air duct configured to supply air to the heater for heating the exhaust gas system of the internal combustion engine;
• and
• a common air filter;
• a processor;
• wherein:
• the first air duct has a first mass flow sensor configured to measure a mass of air flowing through the first air duct, the second air duct has a second mass flow sensor configured to measure a mass of air flowing through the second air duct, a first pressure sensor configured to measure pressure in the first air duct, a second pressure sensor configured to measure pressure in the second air duct, a first temperature sensor configured to measure a temperature of the air flowing through the first air duct, and a second temperature sensor configured to measure a temperature of the air flowing through the second air duct;
• the first and the second air ducts originate from the common air filter;
• the system is configured to diagnose the internal combustion engine with respect to air supply by performing a method that includes:
• operating, by the internal combustion engine, such that the cylinder and the heater of the internal combustion engine transition into one or more predefined operating states;
• monitoring, by the processor, a current state of the cylinder and the heater;
• performing, by the processor, a comparison of at least a subset of measurement values of the first and second mass flow sensors, the first and second pressure sensors, and the first and second temperature sensors of the first and second ducts with one another or with predefined comparison values;
• and
• ascertaining, by the processor, a result of the diagnosis depending on the comparison;
• and
• which of a plurality of predefined comparisons is performed as the comparison depends on to which of the one or more predefined operating states of the cylinder and of the heater the monitoring indicates the current state corresponds.