Component Location
General Description
The heated oxygen sensor is mounted or the front side of Catalytic Converter (warm-up catalytic converter) or in the front exhaust pipe, which detects the oxygen concentration in the exhaust gas. The heated oxygen snesor (HO2S) produces a voltage that varies between 0V and 1V. When the air/fuel ratio is lean, the oxygen concentration in the exhaust gas increases and the front HO2S outputs a low voltage (approximately 0 ~ 0.1 V).
When the air/fuel ratio is rich, the oxygen concentration in the exhaust gas decreases and the front HO2S output a high voltage (approximately 0.8 ~ 1 V). The ECM constantly monitors the HO2S and increases or decreases the fuel injection duration by using the HO2S signal, which is called closed-loop fuel control operation.
DTC Description
If there is no signal or activity within a predetermined time, the ECM judged this as a fault and DTC is set.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | Signal check, wiring interruption
| Contact resistance in connections
Open or Short in signal circuit
Open in ground circuit
Faulty HO2S(UP)
Faulty ECM
|
General Enable Conditions | Dew point end detected
Target lambda = 1
Battery voltage > 10.7V
Exhaust gas temperature (model) : 600? ~ 800?
No upstream O2 sensor error
|
Case1 | Enable Conditions | Sensor voltage : 0.4~0.6V
|
Diagnostic Time | 5 sec
|
Case2 | Enable Conditions | Exhaust gas temperature (model) > 600?
|
Diagnostic Time | Internal resistance > 20 ?
|
MIL ON Condition | NO
|
Schematic Diagram
Signal Waveform
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.