• The PCM operates the HO2S heater according to engine operation conditions as shown in the table below.
Drive duty ratio
Engine operation conditions
30%
• At engine start
• While engine is running except idling
• When a DTC indicating a malfunctioning ECT sensor, TP sensor, or IAT sensor is detected.
100%
• For a fixed period of time after engine start when the engine coolant temperature at engine start is 50°C {122°F} or less than the engine coolant temperature when the engine is stopped from a previous operation (differs from engine coolant temperature at engine start [lower water temperature→longer time]).
Inhibition condition
• Engine speed 4,000 rpm or more
• High load
• HO2S is damaged
• Ignition switch is turned to the ON position while engine is stopped