Es

Relationship between element temperature and impedance:

15,000

1,000

10 5

300 400 500 600 700 800 (572)(752)(932)(1,112)(1,292)(1,472)

15,000

1,000

10 5

300 400 500 600 700 800 (572)(752)(932)(1,112)(1,292)(1,472)

During normal air-fuel ratio feedback control, there are small variations in the exhaust gas oxygen concentration. In order to continuously monitor the slight variations in the HO2 sensor signal while the engine is running, the impedance* of the sensor is measured by the ECM. The ECM determines that there is a malfunction in the sensor when the measured impedance deviates from the standard range. *: The effective resistance in an alternating current electrical circuit. HINT:

• The impedance cannot be measured using an ohmmeter.

• DTC P0136 indicates the deterioration of the HO2 sensor. The ECM sets this DTC by calculating the impedance of the sensor when the typical enabling conditions are satisfied (2 driving cycles).

• DTC P0137 indicates an open or short circuit in the HO2 sensor (2 driving cycles). The ECM sets this DTC when the impedance of the sensor exceeds the threshold 15 kQ.

MONITOR STRATEGY

Related DTCs

P0136: Heated oxygen sensor output voltage (Abnormal voltage output)

P0136: Heated oxygen sensor impedance (Low)

P0137: Heated oxygen sensor output voltage (Low voltage)

P0137: Heated oxygen sensor impedance (High)

P0138: Heated oxygen sensor output voltage (High voltage)

P0138: Heated oxygen sensor output voltage (Extremely high)

Required Sensors/Components (Main)

Heated oxygen sensor

Required Sensors/Components (Related)

Crankshaft position sensor, engine coolant temperature sensor, mass air flow meter and throttle position sensor

Frequency of Operation

Once per driving cycle: Active air-fuel ratio control detection Continuous: Other

Duration

20 seconds: Active air-fuel ratio control detection 90 seconds: Heated oxygen sensor impedance (High) 30 seconds: Heated oxygen sensor impedance (Low) 10 seconds: Output voltage (Stuck high)

MIL Operation

2 driving cycles

Sequence of Operation

None

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