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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 P128A: - Cylinder Head Temperature (CHT) Sensor Circuit Intermittent/Erratic

DTC P128A: - Cylinder Head Temperature (CHT) Sensor Circuit Intermittent/Erratic

DTC P128A: - CYLINDER HEAD TEMPERATURE (CHT) SENSOR CIRCUIT INTERMITTENT/ERRATIC

Description:  Indicates the CHT circuit became intermittently open or shorted while the engine was running.
Possible Causes: 
  • Damaged harness or connector
  • Damaged sensor
Diagnostic Aids:  Monitor the CHT on a scan tool. Look for sudden changes in the reading when the harness is wiggled or the sensor is tapped.
Application  Key On Engine Off  Key On Engine Running  Continuous Memory 
All - - GO to Pinpoint Test DL .