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P0417Secondary Air Injection System Switching Valve "B" Circuit Shorted

The control circuit for the bank 2 secondary air injection switching valve (Valve B) is shorted, drawing current when it should not.

Definition

The PCM monitors current through the Valve "B" switching solenoid driver, which routes secondary air into the bank 2 exhaust during cold starts, and sets P0417 when the circuit is shorted — a solenoid winding shorted internally or a control wire shorted to ground or voltage. Excessive current can blow the AIR fuse or cause the PCM to disable the driver, taking the whole bank 2 air path offline. Driveability is normal, but the MIL illuminates, cold-start emissions rise, and the vehicle will fail an emissions inspection; a circuit stuck energized can also divert air at the wrong times and briefly disturb post-start fuel trims.

Common causes

  • Internally shorted Valve B solenoid winding
  • Control wire chafed to ground along the bank 2 harness run
  • Water intrusion corroding the solenoid or connector
  • Control wire shorted to a power feed
  • Harness melted against exhaust components
  • Faulty PCM driver (rare)

Common misdiagnoses

  • Air pump replaced when the shorted solenoid was blowing the shared fuse
  • PCM replaced for a harness short
  • Fuses replaced repeatedly without isolating the short
  • Bank 2 oxygen sensor replaced for post-start trim complaints

Troubleshooting steps

  1. 1.Measure solenoid resistance

    Ohm the Valve B solenoid; a near-zero reading against a 20-100 ohm typical spec confirms a shorted winding.

  2. 2.Isolate the control wire

    With valve and PCM disconnected, confirm the control wire has no continuity to ground and shows no voltage key-on.

  3. 3.Inspect for heat and water damage

    Trace the bank 2 harness for sections melted near the exhaust and open the valve connector to check for moisture.

  4. 4.Verify current draw after repair

    Command the valve with a scan tool while measuring circuit current and confirm it matches the expected draw for the winding resistance.

  5. 5.Confirm driver operation on a scope

    Watch the PCM driver toggle the circuit cleanly during a commanded AIR test with a known-good valve connected.

  6. 6.Complete the AIR monitor

    Perform a cold-start drive cycle and confirm the secondary air monitor passes with no code reset.

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