Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0412: Secondary Air Injection Solenoid Control Circuit: Description
Ignition voltage is supplied directly to secondary Air Injection (AIR) vacuum control solenoid. Powertrain Control Module (PCM) controls AIR solenoid by grounding control circuit via an internal solid state device called a driver. Primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by PCM. When PCM is commanding a component on, voltage of control circuit should be about zero volts. When PCM is commanding control circuit to a component off, voltage potential of circuit should be about battery voltage. DTC sets when fault detection circuit senses a voltage other than what is expected. PCM will monitor control circuit for a short to ground, short to voltage, open circuit, open solenoid, internally-shorted or excessively low resistance solenoid. When the PCM detects any of the stated malfunctions, this DTC will set and the affected driver will be disabled.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.