Multi-cylinder internal combustion engine with a catalyst heating device

The multi-cylinder internal combustion engine has a mixture forming unit for heat controlled alternating production of rich exhaust gases in a first cylinder bank (2) and lean exhaust gases in a second cylinder bank (3). Each cylinder group is equipped with a separate exhaust pipe (4,5) with a catalyser (6,6') relatively close to the engine and a catalyser (7,7') further away downstream of the engine. A controllable connecting pipe (8) is located upstream of the second catalyser and includes a shut-off component (9) controlled open for the heating of the latter catalyser.