P0413 Secondary Air Injection System Switching Valve A Circuit Malfunction

Understanding P0413: Secondary Air Injection System Switching Valve A Circuit Malfunction

If you drive a modern car with an internal combustion engine, you may have heard of the secondary air injection system (SAIS).

This emission control system helps reduce the amount of harmful pollutants that your vehicle emits into the air by injecting additional air into the exhaust manifold during cold start conditions.

However, if the SAIS encounters a fault, it may trigger a diagnostic trouble code (DTC) that illuminates the check engine light (CEL) on your dashboard. One such code is P0413, which indicates a circuit malfunction in the SAIS switching valve A. In this article, we will explain what P0413 means, what causes it, and how to diagnose and fix it.

What is P0413?

P0413 is a generic OBD-II code that applies to all vehicles manufactured since 1996. It stands for “Secondary Air Injection System Switching Valve A Circuit Malfunction.”

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The SAIS switching valve A is an electronic component that controls the flow of air from the air pump to the exhaust manifold. It is usually located near the air pump, which is driven by a belt or an electric motor and draws fresh air from the air filter. When the engine is cold, the ECM (engine control module) sends a signal to the SAIS switching valve A to open and allow the air to enter the exhaust manifold.

This helps ignite any unburned fuel and heat up the catalytic converter, which reduces emissions and improves combustion efficiency. Once the engine reaches normal operating temperature, the SAIS switching valve A closes to prevent excess air from entering the exhaust system.

What causes P0413?

P0413 can be caused by several factors, including:

  • Faulty SAIS switching valve A: The valve may be stuck open or closed, or its electrical contacts may be corroded or damaged.
  • Failed SAIS air pump: The pump may have seized, worn out, or developed a leak, preventing it from supplying enough air to the switching valve A.
  • Broken or disconnected vacuum hoses: The hoses that connect the switching valve A to the air pump, the exhaust manifold, and the ECM may be cracked, loose, or missing, causing a vacuum leak.
  • Blown SAIS fuse: The fuse that protects the SAIS circuit may have blown due to a short circuit or an overload.
  • Bad ECM: The ECM may have failed, preventing it from sending or receiving the proper signals to operate the SAIS system.

How to diagnose P0413?

To diagnose P0413, you will need a scan tool that can read and erase DTCs, freeze-frame data, and live data. Here are the steps you can follow:

  1. Connect the scan tool to the OBD-II port under the dashboard and turn on the ignition key without starting the engine.
  2. Retrieve the stored DTCs and freeze-frame data from the ECM and verify that P0413 is present.
  3. Check the SAIS fuse and replace it if necessary.
  4. Check the SAIS air pump by listening to its operation, feeling its vibration, or measuring its current draw with a multimeter.
  5. Check the vacuum hoses and connections for any leaks, cracks, or disconnections.
  6. Check the SAIS switching valve A resistance and voltage with a multimeter.
  7. Check the ECM connections for any corrosion, dirt, or damage.
  8. Clear the DTCs and test drive the vehicle to see if P0413 comes back.

How to fix P0413?

To fix P0413, you will need to repair or replace the faulty components that caused it. Here are some common solutions:

  • Replace the SAIS switching valve A and clear the DTCs.
  • Replace the SAIS air pump and/or its relay if it is defective.
  • Repair or replace any damaged vacuum hoses and fix the connections.
  • Replace the SAIS fuse and check for any short circuits or overloads.
  • Replace the ECM if it is damaged or corrupted.


P0413 is a code that indicates a problem with the SAIS switching valve A circuit in your vehicle. It can be caused by various factors, such as a faulty valve, a failed air pump, a broken hose, a blown fuse, or a bad ECM. To diagnose and fix P0413, you need to use a scan tool, check the components, and perform the necessary repairs or replacements. By resolving P0413, you can ensure that your vehicle meets the emission standards and operates efficiently.


  1. Is P0413 a serious code?
    P0413 is not a critical code that affects the drivability or safety of your vehicle, but it may cause the check engine light to stay on and the emissions to exceed the legal limits.
  2. Can I drive with P0413?
    You can drive with P0413, but you may not pass the emissions test or get an inspection sticker until you fix it.
  3. How much does it cost to fix P0413?
    The cost of fixing P0413 depends on the severity of the problem and the labor rates of the repair shop. It may range from less than $100 for a simple repair to several hundred dollars for a complex diagnosis and replacement.
  4. How long does it take to fix P0413?
    The time it takes to fix P0413 depends on the availability of the parts and the skill of the technician. It may take a few hours to a day or more, depending on the complexity of the repair.
  5. How can I prevent P0413 from happening again?
    To prevent P0413 from happening again, you should follow the recommended maintenance schedule for your vehicle, replace the air filter regularly, drive your car regularly to warm up the engine and the SAIS system, and avoid exposing it to extreme weather conditions or environments.