#
HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL OPERATION

BHE014000140T41

## Operation Conditions

• The PCM operates the HO2S when the following conditions are met.

HO2S | Activation condition | Drive signal
--- | --- | ---
Front | • After engine start • After the engine has started and a fixed period of time has elapsed (the elapsed time period after the engine starts is determined by ECT). • ECT is 5°C {41°F} or more. • Battery positive voltage is 9 V or more and less than 16 V. • MAF sensor is normal (no DTC is stored in PCM). | • The PCM outputs a duty signal. • The element temperature is measured by the impedance of the HO2S and a duty ratio is determined.
Rear | • Starter is off • After engine start • After the engine has started and a fixed period of time has elapsed (the time period after the engine starts lenghtens if the ECT falls below 0°C {32°F}. • ECT is 10°C {50°F} or more. • Battery positive voltage is 9 V or more and less than 16 V. • Charging efficiency is the fixed value or less, or during fuel cut. | • The PCM outputs a duty signal. However the duty signal is either 100% or 0%.