Abstract: A lambda probe for an internal combustion engine for the measurement of the fuel-air ratio in the exhaust gas stream of the internal combustion engine is proposed, in which the portion of the oxygen sensor element reaching into the exhaust gas stream is surrounded by a protective element for trapping condensate water. The lambda probe thus constructed can be placed in operation before or immediately after the starting of the internal combustion engine, since the danger of the striking of cold condensate water against the oxygen sensor element and the damage to the lambda probe, which this entails, is prevented.