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In the present investigation, the sensitivity of a SnOz-based sensor in the presence of simulated automotive exhaust gases at different temperatures is investigated. The simulated gas is CO and/or ethane mixed with different amounts of air, to provide the corresponding automotive exhaust gases with different air-to fuel ratios at inlet to the engine. The sensor response is investigated at temperatures ranging from 300-400 DC for CO
and 400-460 DC for ethane. As the air-to-fuel (CO and/or CZH6) weight ratio is varied, the resistance of the sensor shows an S-shape response: a low value for the sensor resistance at low air-to-fuel (ATF) ratios, a transition
region, and a high value at high A TF ratios. The changes in the transition region, depending on the temperature and reducing gas, is as high as one to three orders of magnitude. For CO, the transition region occurs at A TF ratios lower than the stoichiometric value, while for CZH6 it occurs
at values higher than that of stoichiometric. When the simulated gas passes through a catalytic burning chamber upstream of the sensor, a sharp transition in the sensor resistance occurs right at the stoichiometric A TF ratio. Therefore, the sensor can be improved to be used as lambda oxygen sensor.