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Diagnostic Trouble Code: B1257
Diagnostic Trouble Code Name: Air temperature external sensor circuit short to ground
Vehicle Make: Ford
Vehicle Model: Falcon (FG)
Diagnostic Code Entered By: ZerOne
Diagnostic Code Entered On: Wed Oct 06, 2010 11:00 pm
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Please Note: The DTC Information provided has been randomly generated.
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Diagnostic Trouble Code Description:
HO2S Circuit Low Voltage During Power Enrichment Sensor 1
Possible Sensor Faults
ECM
Possible Related Diagnostic Trouble Codes
DTC P1166
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 0-1000?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 1000?mV indicates a rich fuel mixture. An HO2S voltage that decreases below bias voltage toward 0?mV indicates a lean fuel mixture.
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