Patent ID: 6865879

Claim:
A method for determining a fuel quantity at which a burner is operated whose exhaust gas mixes with an exhaust gas of an internal combustion engine in an exhaust-gas system in front of a catalytic converter, the method comprising: measuring a first oxygen concentration in the exhaust gas of the internal combustion engine spatially before the mixing of the exhaust gas of the burner with the exhaust gas of the internal combustion engine; measuring a second oxygen concentration in an intermixed exhaust gas; determining the fuel quantity at which the burner is operated by processing the first oxygen concentration and the second oxygen concentration; processing an air quantity flowing into the internal combustion engine and an air quantity flowing into the burner when the fuel quantity is determined; and determining one of an absolute fuel quantity mKB and a relative fuel quantity based on the following relationship: λB (mLB*λges *λM)/[λM (mLM+mLB)−mLM*λges].