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EmissionsSeverity Low: usually safe to drive

P0412Secondary Air Injection System Switching Valve "A" Circuit

What it means

The ECU sees an electrical fault in the secondary air switching valve circuit.

Symptoms

  • Check engine light
  • Sometimes a whining or roaring noise from the air pump after a cold start
  • Usually no change in how the car drives

Common causes

  • Open or shorted switching valve
  • Wiring or connector fault
  • ECU driver fault

What to check first

  1. Measure the valve resistance
  2. Check supply and control
  3. Inspect the vacuum lines
Can I drive with P0412? Usually yes. P0412 rarely affects how the car drives, but it keeps the check engine light on and can fail an emissions test.

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

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P0412: questions and answers

What does P0412 mean?

P0412: Secondary Air Injection System Switching Valve "A" Circuit. The ECU sees an electrical fault in the secondary air switching valve circuit.

What are the symptoms of P0412?

Check engine light. Sometimes a whining or roaring noise from the air pump after a cold start. Usually no change in how the car drives.

What causes P0412?

Open or shorted switching valve. Wiring or connector fault. ECU driver fault.

How do you diagnose P0412?

1. Measure the valve resistance 2. Check supply and control 3. Inspect the vacuum lines

Can I drive with P0412?

Usually yes. P0412 rarely affects how the car drives, but it keeps the check engine light on and can fail an emissions test.