A method relates to operating an internal combustion engine in the form of an Otto engine, especially of a motor vehicle. Otto engine fuel (i.e., carburetor fuel, spark ignition engine fuel), such as gasoline or ethanol (E85), are directly injected into at least one combustion chamber of the internal combustion engine with at least one fuel injector. Optionally, instead of injecting ignition spark engine fuel or in addition, the internal combustion engine is operated with gas, especially CNG (compressed natural gas) or LPG (liquefied petroleum gas). During operation of the internal combustion engine with gas only, the engine is automatically switched to the operation with spark ignition engine fuel for a predetermined period, or the engine is switched to the operation with spark ignition engine fuel in addition to the operation with gas, in such a manner that a predetermined quantity of the carburetor fuel flows through the at least one fuel injector. The engine is then automatically switched back to the operation with gas only.