| 摘要 |
A control system for an engine includes a limiting current gas sensor includes a pumping cell arranged in the exhaust passage of the engine and an ECU. The ECU is configured to: execute step-up operation for increasing a voltage applied between a pair of electrodes of the pumping cell from a first voltage to a second voltage, then, execute step-down operation for reducing the applied voltage from the second voltage to a third voltage within a second period; acquire an air-fuel ratio of the exhaust gas multiple times within a first period from a start of the step-up operation to a start of the step-down operation; acquire a first waveform characteristic value indicating a characteristic of a waveform of current within the second period; and estimate an actual concentration of sulfur in fuel by using the first waveform characteristic value and the acquired air-fuel ratios. |
