•  Based on the control of the A/F sensor heater and HO2S heaters, a stabilized oxygen concentration is detected even at low exhaust temperatures and feedback control of fuel injection even during cold engine start is made possible for improved cold temperature exhaust emission performance.

•  When exhaust gas temperature is high, the A/F sensor and HO2S are protected from a rise in temperature by the stopping of actuation to the A/F sensor heater and HO2S heaters.