A gas sensor for measuring the concentrations of gases includes a solid body electrolyte, at least three electrodes, and a closed chamber. The doped platinum includes at least 50% by weight platinum and the remainder includes at least one further element selected from the group of solid body electrolytes. In particular, the doped platinum includes between 0.5% by weight to 15% by weight ZrO2 and the remainder is platinum, or the pure platinum is 100% by weight platinum and the gold alloy comprises at least 50% by weight gold and maximally 50% by weight platinum. In particular, the gold alloy includes approximately 85% by weight gold and approximately 15% by weight platinum or the gold alloy comprises at least gold and platinum at a ratio of 85% gold to 15% platinum.