Multiple exhaust gas system and method to regulate an air/fuel ratio of a multi-cylinder internal combustion engine

Exhaust gas device of a multiple cylinder combustion engine (10) comprises two exhaust gas pipes (24, 24') into which one or more cylinders (12, 14, 16, 18) open; a first gas sensor (28) arranged in one of the pipes; and regulating devices (32, 32') for processing the signals produced by the sensors and regulating an air-fuel ratio to be injected into the cylinder depending on the signals. An Independent claim is also included for a process for regulating an air-fuel ratio of a multiple cylinder combustion engine. Preferred Features: A second gas sensor (30, 30') and/or a temperature sensor is arranged in each exhaust pipe downstream of the first gas sensor, especially downstream of a first catalyst (26, 26') or a further catalyst. The first gas sensor is a lambda probe, especially a broad band lambda probe. The second sensor is a lambda probe, especially a quick response lambda probe. The first catalyst is a three-way catalyst.