The normal operating temperature of the HO2S(Heated Oxygen Sensor) ranges from 350 to 850?(662 to 1562?). The HO2S heater greatly decreases the amount of time required for fuel control to become active. The PCM provides a pulse width modulated control circuit to adjust current through the heater. When the HO2S is cold, the value of the resistance is low and the current in the circuit is high. On the contrary, if the temperature in the resistor of the sensor rises, the current drops gradually.
The PCM determines when a rear HO2S heater fault occurs and sets DTC P0036 if measured rear HO2S resistance is lower than the predetermined threshold.
Item
Detecting Condition
Possible Cause
DTC Strategy
Evaluate O2 sensor Element Temperature via measuring Element Resistance
Related fuse blown or missing
Heater control circuit open or short
Power supply circuit open or short
Poor connection or damaged harness
Faulty HO2S
Enable Conditions
O2 sensor pre-heating phase finished (dew point passed)
No relevant failure
Coolant temperature drop since the last engine stop > 25?(77?)
10V< Battery voltage <16V
3.5%< O2 sensor heater control duty < 96.5%
O2 sensor operative ready (to ensure no open circuit failure present)
Threshold Value
Too slow O2 sensor tip-temperature increase after Start causing too low catalyst diagnosis result(O2 Sensor Heater Power < 20% of Nominal Heater Power)
Diagnostic Time
130 sec.
Mil On Condition
2 Driving Cycles
Temp.(?)
Heater Resistance (?)
18 ~ 20
64 ~ 82
3.3 ~ 4.1