| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a heater control device detecting heater currents flowing in a plurality of heaters using one detector and without stopping ordinary heater drive control. <P>SOLUTION: Two air-fuel ratio sensors are arranged in an exhaust passage of an internal combustion engine. The heaters driven according to a duty ratio are built in these air-fuel ratio sensors respectively. ECU sets a first heater in an on condition when starting a new duty cycle (steps 112, 114). A second heater is set in an on condition after a prescribed period t1 (steps 120, 122). For each heater, under a condition where only one heater is on, the heater current flowing through the heater is detected (steps 128, 150). Based on the heater current, the abnormality of each heater is detected during normal control (steps 126-150). <P>COPYRIGHT: (C)2005,JPO&NCIPI |
