P0412: Secondary Air Injection System Switching Valve A Circuit
4 vehicles · 1 makes · $100-$4,000 repair
Most Reported On
P0412 is an OBD-II diagnostic trouble code meaning “Secondary Air Injection System Switching Valve A Circuit.” This emissions code refers to a fault in the secondary air injection (AIR) system's switching valve 'A' circuit. The secondary air injection system pumps fresh air into the exhaust right after a cold start to help the catalytic converter heat up and burn off pollutants faster; the switching valve directs that air flow. The computer sets this code when the electrical control of valve A is open, shorted, or otherwise out of range. It generally affects only cold-start emissions, so you may not notice a drivability change, but it will fail emissions testing. This code is most commonly reported on 2005-2013 Toyota Tundra, 2001-2009 Toyota Sequoia, and 2005-2011 Toyota Tacoma, plus 1 other vehicle, with repair costs ranging from $100 to $4,000.
Common Causes
Typical Repair Cost
Based on 5 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P0412, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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Vehicles Affected (4)
Secondary Air Injection Pump Failure
Secondary Air Injection System Failure (2UZ-FE)
Secondary Air Injection Pump Failure (3UR-FE/i-FORCE)
Secondary Air Injection Pump and Switching Valve Failure on 4.0L V6
Secondary Air Injection Pump/Valve Failure Triggering Limp Mode on 4.7L V8
FAQ
What does P0412 mean?
P0412 stands for "Secondary Air Injection System Switching Valve A Circuit." This emissions code refers to a fault in the secondary air injection (AIR) system's switching valve 'A' circuit. The secondary air injection system pumps fresh air into the exhaust right after a cold start to help the catalytic converter heat up and burn off pollutants faster; the switching valve directs that air flow. The computer sets this code when the electrical control of valve A is open, shorted, or otherwise out of range. It generally affects only cold-start emissions, so you may not notice a drivability change, but it will fail emissions testing.
What are the most common causes of P0412?
The most common causes of P0412 are: Faulty secondary air switching/control valve, Open, shorted, or corroded valve wiring/connector, Blown fuse or faulty relay for the AIR system, Failed secondary air injection pump, Stuck or carbon-clogged air valve, Vacuum supply leak to the control valve, Faulty engine control module (PCM) — rare. The specific cause varies by vehicle.
How much does it cost to fix P0412?
Repair costs for P0412 range from $100 to $4,000, depending on the vehicle and root cause.
Which vehicles are affected by P0412?
Au7o has documented P0412 across 4 vehicle models from 1 manufacturers: Toyota.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.