P0416 — Secondary Air Injection System Switching Valve B Circuit Open

What P0416 means

P0416 is the standardized powertrain DTC for “Secondary Air Injection System Switching Valve B Circuit Open.” The code identifies the monitored condition; it does not by itself prove which part failed.

How to interpret the code wording

“Circuit/Open” points first toward circuit integrity: connector pin fit, broken wiring, missing power/ground, excessive resistance, or an open load/actuator. Confirm voltage and voltage drop under load before condemning a control module.

Possible symptoms

• Check Engine Light
• Often no noticeable drivability symptom
• Possible unusual pump noise during cold start
• Emissions-readiness failure

Causes to test

These are diagnostic possibilities, not a statistical parts-replacement ranking. Vehicle-specific service information takes priority.

• Secondary-air pump or power/relay/fuse problem
• Stuck or leaking air switching/check valve
• Vacuum/control-solenoid problem where used
• Blocked secondary-air passages
• Pressure/flow sensor or wiring fault on monitored systems
• Water intrusion or condensation damage in pump/valves on some designs

Step-by-step diagnostic workflow

1. Determine whether the code is electrical, flow-related, or bank-specific.
2. During the commanded cold-start window, verify pump operation and electrical supply.
3. Check switching/check valves and control vacuum/solenoids as applicable.
4. Verify actual air flow/pressure response and inspect passages for restriction.
5. Follow vehicle-specific service information because system layouts vary substantially.
6. Clear codes only after repair, then complete an appropriate drive cycle and verify the code and symptoms do not return.

Scan data worth checking

• Secondary-air command/status
• O2/A/F response during air injection
• Air pressure/flow sensor data where equipped
• Coolant temperature and cold-start state
• Related relay/solenoid commands

Severity and drivability

Usually low for immediate drivability, but the system should be repaired for emissions compliance and to prevent related component damage.

Stop driving and investigate immediately if there is a flashing MIL, oil-pressure warning, overheating, fuel leakage, severe misfire, major loss of power, abnormal mechanical noise, or a transmission that is slipping badly.

Common diagnostic mistakes

• Replacing the pump without checking valves, passages, and power supply
• Testing only on a warm engine when the monitor will not command the system
• Ignoring water intrusion that can damage a replacement pump

Related generic codes