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Home >> Subaru >> 2015 >> WRX Limited, Automatic CVT Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 7 (Engine Controls (Diagnostics) (H4DOTC) (STI)) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P2257 Air System Control "A" Circuit Low >> Wiring Diagram

DTC P2257 Air System Control "A" Circuit Low: Wiring Diagram

WARNING: This page is about a different variant/trim than selected.
Fig 1: Air System Control "A" - Wiring Diagram (Low)
G10265841Courtesy of SUBARU OF AMERICA, INC.
DIAGNOSTIC PROCEDURE

Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND SECONDARY AIR PUMP RELAY CONNECTOR. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from ECM.
  3. Remove the secondary air pump relay.
  4. Measure the resistance of harness between ECM connector and secondary air pump relay connector.

    Connector & terminal 

    (B135) No. 27 - (F9) No. 13: 

Is the resistance less than 1 Ω? Go to step . Repair the harness and connector.
NOTE: In this case, repair the following item:

  • Open circuit in harness between ECM connector and secondary air pump relay connector
  • Poor contact of coupling connector
2 CHECK HARNESS BETWEEN ECM AND SECONDARY AIR PUMP RELAY CONNECTOR. 
Measure the resistance between ECM connector and chassis ground.
Connector & terminal 
(B135) No. 27 - Chassis ground: 
Is the resistance 1 MΩ or more? Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.
NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
Repair the short circuit to ground in harness between ECM connector and secondary air pump relay connector.