P0412 Fault Code

Secondary Air Injection System Switching Valve A Circuit Malfunction

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0412 fault code indicates that there is a problem with the Secondary Air Injection System Switching Valve A. This system is designed to reduce emissions by injecting air into the exhaust stream during cold starts. When this code appears, it typically means that the switching valve is not functioning as intended.

• The secondary air injection system helps in reducing harmful emissions.
• It operates primarily during engine start-up to improve catalyst efficiency.
• A malfunction can lead to increased emissions and reduced fuel efficiency.

What are the symptoms of the P0412 code?

When the P0412 code is present, you may notice some of the following symptoms:

• Check Engine Light illuminated on the dashboard.
• Decreased fuel efficiency due to improper air-fuel mixture.
• Increased emissions, potentially causing failure in emissions testing.
• Rough idling or difficulty starting the engine in cold weather conditions.
• Unusual noises from the engine compartment, particularly at startup.

What causes the P0412 code?

Several factors can trigger the P0412 error code, including:

• Faulty air injection control valve.
• Electrical issues such as short circuits or open circuits in the wiring.
• A clogged or damaged air supply hose.
• Malfunctioning vacuum or pressure sensors associated with the air injection system.
• ECM (Engine Control Module) software errors or failures.

How to fix P0412?

To resolve the P0412 fault code, the following steps are recommended:

• Start with a diagnostic scan to confirm the presence of the code and any additional codes.
• Inspect the air injection control valve for any visible signs of damage or malfunction. Replace if necessary.
• Check wiring and connectors for damage, corrosion, or loose connections.
• Inspect and clean any clogged air supply hoses.
• If all components appear functional, consider updating or reprogramming the ECM.
• Always ensure to reset the vehicle’s computer after repairs and retest to confirm the fix.