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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 P2258: - Secondary Air Injection (Air) System Control A Circuit High

DTC P2258: - Secondary Air Injection (Air) System Control A Circuit High

DTC P2258: - SECONDARY AIR INJECTION (AIR) SYSTEM CONTROL A CIRCUIT HIGH

Description:  The AIR system monitor circuit is high, indicating the secondary AIR pump is on although the secondary AIR pump was commanded off by the powertrain control module (PCM).
Possible Causes: 
  • AIR relay fault - stuck closed
  • Secondary AIR pump fault - circuit open in motor
  • Open ground to secondary AIR pump
  • Open AIR monitor circuit between the secondary AIR pump and the PCM
  • Short to voltage in the AIR relay to secondary AIR pump voltage circuit
Diagnostic Aids:  The AIR monitor circuit PCM input contains a pull up voltage through a resistance internal to the PCM. This voltage is normally held low by the resistance path through the secondary AIR pump when the secondary AIR pump is off.
Application  Key On Engine Off  Key On Engine Running  Continuous Memory 
All GO to Pinpoint Test HM .