HO2S(S2) is in the rear side of Catalytic Converter to check the proper operation of catalyst. Oxygen density after the catalytic converter has to be within specific range (around 0.5V when there is no acceclation and deceleration.)
If the oxygen density changes in accordance with HO2S(S1), it means the poor performance of catalytic converter.
In case the sensor output is 0.4~0.52 V during 600sec or the internal resistance is over 40 ㏀ under enable conditions, ECM sets DTC P0136.( This DTC might be caused by the malfunction of Heater circuit, so, check the heater circuit first. )
Item | Detecting Condition | Possible Cause | |
DTC Strategy |
•
Signal check | 1. Poor connection 2. Open or short in signal circuit 3. S2 | |
General Enable Conditions |
•
Dew point end detected
•
Battery voltage > 11V
•
Exhaust Gas temperature = 350℃~800℃
•
No upstream O2 sensor heater error | ||
Case1 | ThresholdValue |
•
Sensor voltage : 0.4~0.52 V | |
DiagnosticTime |
•
600 sec | ||
Case2 | ThresholdValue |
•
Rate of heater pulse coupling to sensor signal > 5 times per every 10 heating pulses | |
MIL ON Condition |
•
3 driving cycle | ||
※ S2 : upstream oxygen sensor / S2 : downstream oxygen sensor
If you release the accelerator pedal suddenly after engine running about 4000 rpm, fuel supply will stop for short period and the O2 sensor service data in the Hi-Scan (Pro) will display values 200mV or lower. When you suddenly press on the accelerator pedal down, the voltage will reach 0.6 ~ 1.0 V. When you let the engine idle again, the voltage will fluctuate between 200 mV or lower and 0.6 ~ 1.0 V. In this case, the O2sensor can be determined as good.
