What it means
Secondary Air Injection System Switching Valve B Circuit Open: the circuit is open. Likely a broken wire, disconnected connector, or failed component.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Switching valve B routes secondary air during the AIR system's cold-start routine. The ECU monitors the valve B electrical circuit and sets P0416 when it detects an open path, which may be caused by a broken wire, disconnected terminal, or open solenoid winding. The valve may not operate when commanded.
Common causes
Most likely first.
- Open winding or wire
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
Symptoms
- Check engine light on
- Failed emissions inspection
- Possible roughness during cold start
How to diagnose it
- Review freeze-frame data and related AIR codes to confirm the fault is associated with valve B during a cold-start check.
- Inspect the valve B connector for disconnection, corrosion, damaged terminals, or a pin pushed back into the connector body.
- Check the valve B solenoid winding for continuity using the manufacturer's specification.
- Follow the wiring diagram to test the valve B circuit for an open between the connector and the control module.
- If the solenoid and harness pass, inspect the control module connector and driver circuit for a poor connection or internal fault.
Common fixes
- Reconnect and secure the valve B connector.
- Repair a broken wire or terminal in the valve B circuit.
- Replace the valve B solenoid if its winding is open.
- Repair the control module connection or driver only after verifying the valve and harness.
Can I keep driving?
The vehicle is generally driveable, but secondary air may not flow through the valve B path during cold starts, raising emissions and risking an inspection failure. If cold-start roughness occurs, avoid unnecessary trips until the open circuit is repaired.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.