In order to control emissions of the CO, HC and NOx components of the exhaust gas, heated oxygen sensor (HO2S), mounted on the front side and rear side of catalytic converter, detects the oxygen content in the exhaust gas. The front HO2S signal is used to control air/fuel ratio (closed loop fuel control) and the rear HO2S signal is used to monitor front HO2S and catalyst for proper operation.The HO2S requires a minimum temperature to operate properly and provide a closed loop fuel control system. The HO2S contains the heater element to reduce its warming-up time and ensure its performance during all driving conditions.The ECM controls this heater element by duty cycle. The main relay supplies voltage to the heater and the ECM provides a ground circuit for activating the heater.
If the internal resistance of heater is over the threshold value under enable conditins, ECM sets DTC P0141.
Item
Detecting Condition
Possible Cause
DTC Strategy
Heater current check
Poor connection
Open or short to ground in signal circuit
S2
General
Enable
Conditions
Exhaust gas temperature (modeled) 200~550°C
Intake air temperature > -6?
Battery voltage 10.7~16.1V
Threshold Value
Internal resistance > threshold f (cat. temp., heater power)
Diagnostic Time
Above 6 sec
MIL ON Condition
3 driving cycle
? S2 : upstream oxygen sensor / S2 : downstream oxygen sensor
Specification
Heater Resisstance(?)
Approx. 9.0(20?)
The HO2S requires a minimum temperature to provide a closed loop fuel control system. So the HO2S contains a heater element to reduce its warm-up time and ensure its performance during all driving conditions. The HO2S heater is controlled ON after engine start except for Cold condition and high speed accelleration. The ECM controls this heater element by duty cycle. The main relay supplies voltage to the heater and the ECM provides a ground circuit for activating the heater.