P0419: Secondary Air Injection System Relay B Circuit
Severity: low
What it means: P0419 means the engine computer found an electrical problem in the circuit for secondary air injection relay 'B'. The secondary air system pumps fresh air into the exhaust for a short time after a cold start to cut emissions. On Toyota and Lexus V8s, P0419 is commonly tied to the bank 2 side of this system.
Safe to drive? Usually yes. It's an emissions system, but it can turn on other warning lights (such as VSC on Toyota/Lexus) and will fail an emissions test.
Common symptoms
- Check engine light, often after a cold start
- VSC, TRAC or slip lights on some Toyota/Lexus models
- May go away and come back
Likely causes, ranked
- Relay, fuse or pump driver faultDIY or shop
- Wiring or connector problemShop
- Failed secondary air pumpShop
Vehicle-specific notes
- 2008–2015 Lexus LX 570: Owners report P0419 together with P2447 and VSC/4LO lights after cold starts. Read the full answer · Source
DIY or shop?
Checking fuses and relays is DIY. Testing the pump and wiring may need a shop.
Before you replace parts
- Read all codes; secondary air codes often set in pairs (pump and valve, or both banks).
- Check fuses and relays for the air pump circuit.
- Command the pump on with a scan tool or apply power to test it, and listen for it running.
- Inspect hoses and the air switching (check) valves for water, blockage or sticking.
- Check your VIN for recalls, service bulletins and extended coverage.
Safety / mechanic note
Verify with a mechanic. With VSC/traction control switched off, the vehicle has less traction help on slippery roads. A code points to a circuit or system, not always a specific part.