Diagnostic Trouble Code: 159
Diagnostic Trouble Code Name: Mass Air Flow (MAF) sensor out of calibration
Vehicle Make: Ford
Vehicle Model: Falcon (EL)
Diagnostic Code Entered By: ZerOne
Diagnostic Code Entered On: Wed Oct 06, 2010 11:00 pm
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Diagnostic Trouble Code Description:
O2 Sensor Heater Circuit
Possible Sensor Faults
ECM
Possible Related Diagnostic Trouble Codes
DTCP0135, P0141, P0155, or P0161
Circuit / System Description
The heated oxygen sensor (HO2S) must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by the ignition?1 voltage circuit through a fuse. With the engine running, ground is provided to the heater by the HO2S heater low control circuit, through a low side driver within the engine control module (ECM). The ECM commands the heater ON or OFF to maintain a specific HO2S operating temperature range. The ECM determines the temperature by measuring the current flow through the heater. When the heater is in the ON state, the ECM will pulse the heater OFF for a duration of 50?ms, once per second. When the heater is in the OFF state, the ECM will pulse the heater ON for a duration of 50?milliseconds, once per second. The ECM monitors the heater current with the engine running. The ECM also calculates the heater resistance on a cold start. Both diagnostics will only run once per ignition cycle.
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