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Diagnostic Trouble Code: B1251
Diagnostic Trouble Code Name: Air Temperature Internal Sensor Circuit Open Input floats > 4.56V
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 Signal Stuck Rich Bank 1 Sensor 2
Possible Sensor Faults
ECM
Possible Related Diagnostic Trouble Codes
DTC P2271 or P2273
Circuit / System Description
The engine control module (ECM) supplies a voltage near 450?mV between the heated oxygen sensor (HO2S) high signal circuit and the low reference circuit. The HO2S varies the voltage over a range from about 1,000?mV when the exhaust is rich, down through about 10?mV when the exhaust is lean. The ECM monitors and stores the HO2S voltage information. The ECM evaluates the HO2S voltage samples in order to determine the amount of time that the HO2S voltage was out of range. The ECM compares the stored HO2S voltage samples taken within each sample period and determines if the majority of the samples are out of the operating range. The ECM test for the following conditions:
The ECM monitors the HO2S voltage to determine if the signal voltage goes above a predetermined threshold within a certain amount of time. If the ECM determines that the signal voltage remains below a threshold, the ECM will command the fuel system rich to determine if the HO2S signal voltage can be forced above the threshold within a certain amount of time.
The ECM monitors the HO2S voltage during power enrichment to ensure that the signal voltage goes above a predetermined threshold during power enrichment.
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