What it means
Secondary Air Injection System Switching Valve B Circuit: an electrical fault is present in the circuit.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The AIR switching valve B directs secondary air through a separate valve path during cold starts. The ECU monitors the electrical circuit that operates valve B. P0415 indicates an electrical fault in that circuit, but does not by itself identify an open or short.
Common causes
Most likely first.
- Switching valve B solenoid failure
- Open or shorted wiring in the valve circuit
- Loose, damaged, or corroded connector
- Control module driver fault
Symptoms
- Check engine light on
- Failed emissions inspection
- Possible roughness during cold start
How to diagnose it
- Check freeze-frame data and related AIR codes to identify when the valve B fault occurred and whether valve A or pump circuits also have codes.
- Locate switching valve B using vehicle service information and inspect its connector and wiring for looseness, corrosion, chafing, or heat damage.
- Test the valve B solenoid for an open or short using the manufacturer's procedure and specification.
- Use the wiring diagram to check valve B circuit continuity and for shorts to power or ground.
- If the valve and harness pass, verify the circuit's power supply and ECU driver before concluding the module has failed.
Common fixes
- Clean and secure a loose or corroded valve B connector.
- Repair damaged wiring in the valve B circuit.
- Replace the switching valve B solenoid if it fails its electrical test.
- Repair the ECU driver circuit only after confirming the valve, harness, and power supply are sound.
Can I keep driving?
This fault usually allows normal driving, but the AIR cold-start emissions function may be impaired and the vehicle may fail an emissions inspection. If the engine runs roughly during cold starts, reduce unnecessary short trips until the valve B 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.