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 is able to detect 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.
ECM sets DTC P0136 if the ECM detects that the rear HO2S signal circuit is open.
Item
Detecting Condition
Possible Cause
DTC Strategy
? Voltage range check
? Open in signal harness
? Open in ground harness
? Poor connection or damaged harness
? Faulty Heated O2 Sensor(HO2S)
Enable Conditions
? O2 sensor operative readiness detected
? O2 sensor pre-heating phase finished
? No relevant failure
? 10V< Battery voltage <16V
Threshold Value
? 0.37V <Down HO2S < 0.48V and sensor element resistance > 60k?
Diagnostic Time
? 30sec.
Test Condition
Scan Tool Parameter
O2 SNSR VOL.-B1/S1
O2 SNSR VOL.-B1/S2
Normal Value when circuit is normal
Idle after warm up
Signal is switching from rich(above 0.45V) to lean(below 0.45V) a minimum of 3 times in 10 seconds.
above 0.6V
HO2S(B1S1) signal circuit open
Approx. 0.43~0.45V
-
HO2S(B1S2) signal circuit open