The rear heated oxygen sensor is mounted on the rear side of the Catalytic Converter (warm-up catalytic converter) or in the rear exhaust pipe, which detects the catalyst efficiency. The rear heated oxygen sensor (HO2S) produces a voltage between 0V and 1V. This rear heated oxygen sensor is used to estimate the oxygen storage capability. If a catalyst has good conversion properties, the oxygen fluctuations are smoothed by the oxygen storage capacity of the catalyst. If the conversion provided by the catalyst is low due to aging, poisoning or misfiring, then the oxygen fluctuations are similar to signals from the front oxygen sensor.
If circuit voltage is higher than 4.5V after 5V is applied to the HO2S output line via a resistor, the PCM determines that a fault exists and a DTC is stored.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Circuit voltage(Vf) is monitored. | ● Poor connection ● Open in HO2S circuit ● Faulty HO2S ● Faulty PCM |
Enable Conditions | ● Engine coolant > 81℃ | |
● Engine speed >1187rpm | ||
● Load value >300mmHg | ||
Threshold value | ● Circuit voltage ≥4.5V | |
Diagnosis Time | ● Continuous |
Signal Voltages | Voltage will Appox. 0.5 ~ 0.7 Volts |
