P0415
AIR System Switching Valve B Circuit
Secondary air injection (emissions)
Generic OBD-II
Medium
What it means
P0415 means the engine computer has found a fault in the secondary air injection (AIR) system's switching valve B circuit. The AIR system pumps fresh air into the exhaust at cold start to cut warm-up emissions. This is an emissions fault — the car normally drives fine, but the check-engine light stays on and it can fail an emissions test.
Medium
Can I keep driving? Yes — this is an emissions-control fault that doesn't affect normal driving; fix it to clear the light and pass emissions.
Common symptoms
What you'll notice
- Check-engine light on
- Fails an emissions test
- Occasionally rougher running just after a cold start
Common causes
Most likely first
- Failed secondary air injection switching valve BLikely
- Damaged wiring or a faulty connector in the circuitCommon
- Corroded electrical connectionsCommon
- Failed ECM (rare)Less often
How to diagnose & fix
Work through it in order
- Inspect the switching valve B connector and wiring for damage or corrosion.
- Test the valve's electrical operation and its vacuum/air supply.
- Replace the switching valve B if it fails testing.
- Repair any damaged wiring in the circuit.
- Only consider the ECM after the valve and wiring check out.
FAQ
Quick answers
Is it safe to drive with P0415?+
Yes. The secondary air system only runs briefly at cold start to cut warm-up emissions, so a fault here doesn't affect everyday driving. The main consequence is the check-engine light and an emissions-test failure.
Can I just clear P0415?+
It will return once the ECM next tests the AIR system. The valve or its wiring needs repair to keep the code away.
Related codes
Often seen with P0415
Read & clear P0415 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX