AIR System Switching Valve B Circuit Open
What it means
P0416 means the engine computer detects an open circuit in the secondary air injection system's switching valve B. The secondary air system pumps fresh air into the exhaust at cold start to help the catalytic converter light off and cut emissions. A fault here is an emissions issue — it won't stop the engine from running or starting, but it will usually cause an emissions-test failure.
Can I keep driving? You can keep driving. The secondary air system only runs briefly at cold start for emissions, so a fault won't cause a no-start — but the car will likely fail an emissions test.
Common symptoms
What you'll notice
- Check-engine light on
- Failed emissions test
- Possible rougher running for a short time right after a cold start
Common causes
Most likely first
- Open circuit in the secondary-air switching valve B control (failed valve solenoid)Likely
- Broken, chafed, or corroded wiring in the valve circuitCommon
- Loose or corroded connector at the valveCommon
- Failed ECM or relay driving the valve (rare — check wiring first)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and confirm the code is on switching valve B.
- Inspect the valve connector and wiring for an open, corrosion, or a loose pin.
- Measure the valve solenoid's resistance and compare with spec for an open winding.
- Check the valve's power/ground and the ECM control circuit for continuity.
- Replace the switching valve if its coil is open, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0416?+
Can I just clear P0416?+
Related codes
Often seen with P0416
Read & clear P0416 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.