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P0412 OBD2: Secondary Air Injection System Switching Valve "A" Circuit

P0412 OBD2: Secondary Air Injection System Switching Valve “A” Circuit

The P0412 code is an OBD-II diagnostic trouble code that indicates an issue with the Secondary Air Injection System. This system is crucial for reducing harmful emissions by injecting fresh air into the exhaust system during cold starts, helping to burn off excess fuel and improve efficiency.

What Does the P0412 Code Mean?

OBD-II Code P0412 is defined as a fault in the Secondary Air Injection System Switching Valve “A” Circuit. This means that the engine control module (PCM) has detected a malfunction in the circuit that controls the switching valve of the secondary air injection system.

What Causes the P0412 Code?

Several issues can trigger the P0412 code, including:

  • Clogged or disconnected vacuum hose
  • Powertrain Control Module (PCM) failure
  • Secondary air pump control valve failure
  • Secondary air pump switching valve failure
  • Wiring issue

What Are the Symptoms of the P0412 Code?

The symptoms associated with the P0412 code may include:

  • Illuminated check engine light
  • Increased emissions
  • Rough engine idle during cold starts

How Serious Is the P0412 Code?

While the P0412 code is classified as a moderate severity issue, it does not pose an immediate threat to the vehicle’s safety or drivability. However, it is important to diagnose and address the problem in a timely manner to avoid more serious issues down the road.

How to Diagnose the P0412 Code

Diagnosing the P0412 code requires a systematic approach, including:

  • Using an OBD-II scanner to confirm the code and check for any related codes
  • Inspecting the wiring and connectors for any signs of damage or corrosion
  • Testing the secondary air pump and its components for proper operation
  • Checking for vacuum leaks in the hoses

Common Repairs for the P0412 Code

Repairs for the P0412 code may include:

  • Replacing faulty wiring or connectors
  • Repairing or replacing the secondary air pump control valve
  • Fixing or replacing any clogged or disconnected hoses
  • Replacing the PCM if it is determined to be defective

How Much Does It Cost to Fix the P0412 Code?

The cost to repair the P0412 code can vary widely based on the specific issues identified. Typical repair costs may range from $100 to $600, depending on whether you need to replace hoses, valves, or the PCM itself.

Can I Fix the P0412 Code Myself?

If you have experience with automotive repairs and access to the necessary tools, you may be able to diagnose and fix the P0412 code yourself. However, for those who are not familiar with vehicle systems, it’s advisable to consult with a professional mechanic to ensure the problem is accurately diagnosed and repaired.

About JC Landry

JC is the Senior Editor at eManualOnline.com, GarageSpot.com, and Drive-My.com, as well as the Webmaster of TheMechanicDoctor.com, only to name a few. He's been a certified Master Mechanic for 15 years, working for various car dealers and specialized repair shops before turning towards blogging about cars and EVs in the hope of helping the next generation of automotive technicians. He also loves cats, Johnny Cash and Subarus.

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