The rear heated oxygen sensor is mounted on the rear side of the Catalytic Converter which is able to detect 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 the PCM detects short to battery in heater under detecting conditions, PCM sets P0058. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Detects a short to battery | ● Poor Connection ● Short to battery in control circuit ● HO2S(B2/S2) ● PCM |
Enable Conditions | ● No disabling Faults ● Engine Running ● 11V ≤ Battery Voltage ≤ 16V | |
Threshold value | ● Short to battery | |
Diagnosis Time | ● Continuous (More than 5 seconds failure for every 10 seconds test) | |
MIL On Condition | ● 2 Driving Cycles |
Heater | |
Resistance (Ω) | 3.0~4.0Ω[21℃(69.8℉)] |
The HO2S requires a minimum temperature to provide a closed loop fuel control system. So the HO2S contains a heater element to reduce its warm-up time and ensure its performance during all driving conditions. The PCM controls this heater element by duty cycle. The main relay supplies voltage to the heater and the PCM provides a ground circuit for activating the heater.
