P0412: Secondary Air Injection System Switching Valve A Circuit Malfunction
What to do
Driveable with no symptom you would notice, but it will fail an emissions test.
What this code means
An electrical fault in the circuit controlling the secondary air switching valve. The switching valve directs pump output into the exhaust when required and isolates it the rest of the time; it may be operated electrically or by a vacuum solenoid that the module switches.
This is a circuit complaint rather than a flow complaint, so the diagnosis is electrical: supply, ground, and the winding itself. Where the valve is vacuum-operated, remember there are two things called the valve — the electrical solenoid the module drives, and the pneumatic valve it controls. This code concerns the first.
Likely causes
Start here
- Faulty secondary air switching valve · moderate
- Corroded or loose connector · easy
- Open or shorted solenoid winding · easy
Less common
- Damaged wiring harness near exhaust heat · moderate
Rare
- Control module driver failure · specialist
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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