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Home >> Mercury >> 2009 >> Mariner Base, 2.5 7, AWD >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Powertrain DTC Charts & Descriptions (Except Diesel & Hybrid) >> DTC Diagnosis >> DTC P0111: - Intake Air Temperature (IAT) Sensor 1 Circuit Range/Performance

DTC P0111: - Intake Air Temperature (IAT) Sensor 1 Circuit Range/Performance

DTC P0111: - INTAKE AIR TEMPERATURE (IAT) SENSOR 1 CIRCUIT RANGE/PERFORMANCE

Description:  Indicates the IAT rationality test has failed. This DTC indicates that the IAT value is higher than a calibrated value and could prevent one or more on-board diagnostic (OBD) monitors from completing.
The powertrain control module (PCM) runs this logic after an engine off and a calibrated soak period (typically 6 hours). This soak period allows IAT and engine coolant temperature (ECT) or cylinder head temperature (CHT) to stabilize and not differ by more than a calibrated value. DTC P0111 sets when the IAT at engine start exceeds the ECT or CHT by more than a calibrated value, typically 17°C (30°F).
Possible Causes: 
  • IAT Sensor
Diagnostic Aids:  Make sure the IAT and the CHT or ECT are similar when the engine is cold.
Application  Key On Engine Off  Key On Engine Running  Continuous Memory 
All GO to Pinpoint Test DA .