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Diagnostic Trouble Code: 7

Diagnostic Trouble Code Name: Automatic Temperature Controller

Vehicle Make: Chevrolet

Vehicle Model: Epica (V250)

Diagnostic Code Entered By: ZerOne

Diagnostic Code Entered On: Wed Oct 06, 2010 11:00 pm

Please Note: The DTC Information provided has been randomly generated.

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Diagnostic Trouble Code Description: 

H02S Circuit High Voltage During Decel Fuel Cut-Off Bank 2 Sensor 2

Possible Sensor Faults
ECM

Possible Related Diagnostic Trouble Codes
DTC P2A01 or P2A04

Circuit / System Description
The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. The control module supplies the HO2S with a reference, or bias voltage of about 450?mV. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,000?mV. This voltage will fluctuate above and below the bias voltage. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control module uses the HO2S voltage to determine the air-to-fuel ratio. An HO2S voltage that increases above bias voltage toward 1,000?mV indicates a rich fuel mixture. An HO2S voltage that decreases below bias voltage toward 0?mV indicates a lean fuel mixture.

The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed Loop earlier and the control module to calculate the air-to-fuel ratio sooner.

The HO2S utilizes the following circuits: