P0419 — Problem with secondary air injection control circuit B
The code indicates an electrical issue in the secondary air injection system's control circuit B. This system helps reduce emissions by injecting air into the exhaust to burn off pollutants. The fault could be caused by wiring problems, a faulty relay, or a bad air pump.
Common causes
The cause is almost always one of a few things. Here they are — P0419 rarely comes from anything outside this list:
- Blown fuse or faulty relay in air injection circuit
- Damaged or corroded wiring/connectors
- Faulty secondary air injection pump or valve
- Defective control module or sensor
Where to start
In the order a sensible mechanic would work — the cheap checks first, the expensive replacements only after:
- Check and replace blown fuses or faulty relays
- Inspect and repair damaged wiring or connectors
- Test and replace secondary air injection pump or valve if needed
- Scan and test control module for faults
That is what holds for P0419 in general. From here it depends on your engine — tell me which car it is and what it does, and I will give you the steps for it: real procedures, torque figures and diagrams instead of general advice.
Why TorqFix for your car?
Above is what the code means and why it appears. TorqFix goes further — it gives you specific procedures, torque values, wiring diagrams and pinouts for your exact engine, not generic steps for every car. Real workshop data (127,000+ diagrams, 10,000+ procedures), interpreted by AI in your language.
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Code breakdown
🔧 Related repair procedures
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- AUDI: Removing and installing catalytic converter
- AUDI: Removing and installing front exhaust pipe (left-side) with catalytic converter - vehicles with multitronic gearbox
- AUDI: Removing and installing catalytic converter - vehicles with two turbochargers
- AUDI: Removing and installing catalytic converter with exhaust pipe - vehicles with engine code letters AVF, AWX
- AUDI: Checking Lambda probe and Lambda control after catalytic converter
- VW: Removing particulate filter with NOx storage catalytic converter
Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
The same code can mean different things on different makes. Match the meaning to your make before acting on it.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
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