Component Location
General Description

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.

DTC Description

ECM sets DTC P0137 if the ECM detects signal voltage lower than the possible range of a properly operating rear heated oxygen sensor (HO2S).

DTC Detecting Condition

ITEM

DETECING CONDITION

POSSIBLE CAUSE

DTC Strategy

●Sensor voltage low

● Short to ground in signal harness

● Contact resistance in connectors

● Faulty Heated O2 Sensor.(HO2S)

Enable Conditions

●Sensor preheating and full heating phases finished

●Battery voltage ＞10V

Threshold Value

●Sensor voltage ＜0.02V and element resistance ＜10Ω

Diagnostic Time

● 1 sec.

Schematic Diagram
Signal Waveform
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