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.
If the sensor output is below 0.06 V under enable conditions, ECM sets DTC P0137.
(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, low | 1. Poor connection 2. Short to ground 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 | Enable Conditions |
•
Engine speed : 1200~2520 rpm
•
Rear O2 sensor feed back control - active | |
DiagnosticTime |
•
25 sec | ||
Case2 | Enable Conditions |
•
Sensor in cold condition | |
DiagnosticTime |
•
0.1 sec | ||
Threshold Value |
•
Sensor voltage < 0.06V | ||
MIL ON Condition |
•
3 driving cycle | ||
※ S1 : 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.
