P0419
AIR System Control B Circuit
Secondary air injection / emissions
Generic OBD-II
Medium
What it means
P0419 means the computer detected a fault in the control circuit for the secondary air injection (AIR) system's B relay. That system briefly pumps air into the exhaust at cold start to help the catalyst warm up, so this is an emissions code with little effect on how the car drives. It usually traces to the relay, its wiring, or a connector.
Medium
Can I keep driving? Safe to drive; the secondary air system only runs briefly at cold start, so this is mainly an emissions fault that won't affect everyday driving.
Common symptoms
What you'll notice
- Check-engine light on
- Usually no change in how the vehicle drives
- May fail an emissions/readiness test
- Possible extra noise from the air pump at cold start
Common causes
Most likely first
- Faulty secondary air injection relay/control BLikely
- Open or short in the relay control wiringCommon
- Loose or corroded electrical connectorCommon
- Failed engine control module (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and confirm it's the secondary air (AIR) system control B circuit.
- Inspect the relay and control wiring for opens, shorts, and corrosion.
- Command the secondary air system with a scan tool and confirm the relay/pump responds.
- Replace the relay or repair the wiring as indicated. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0419?+
Yes — the secondary air system only helps warm the catalyst at cold start, so this fault won't affect normal driving. Fix it before an emissions test.
Can I just clear P0419?+
It will clear, but returns until the relay control circuit is repaired.
Related codes
Often seen with P0419
Read & clear P0419 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