P0416 Secondary Air Injection System Switching Valve B Circuit Malfunction

If you own a vehicle and have ever experienced a malfunction indicator light (MIL) illuminating on your dashboard, you know how nerve-wracking it can be.

There are many different reasons why this can happen, but one of them is a secondary air injection system switching valve B circuit malfunction, also known as trouble code P0416. In this article, we’ll explain what this code means, what can cause it, and what you can do to fix it.

What is a secondary air injection system?

Before we can dive into the specifics of P0416, we first need to understand what a secondary air injection system (SAIS) is and what it does.

This system is used in vehicles to reduce emissions by injecting fresh air into the exhaust system to help burn off any remaining fuel that hasn’t been combusted. This process helps to lower harmful emissions and reduce the environmental impact of driving.

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What is trouble code P0416?

P0416 is a diagnostic trouble code (DTC) that indicates a malfunction within the SAIS switching valve B circuit. This code is specific to vehicles with a SAIS, and it is most commonly found in Toyota, Lexus, and GM vehicles.

What causes P0416?

There are several possible causes of P0416. The most common cause is a faulty SAIS switching valve B, which is responsible for controlling the flow of air into the system. Other potential causes include a damaged or disconnected vacuum line, a malfunctioning SAIS pump, or a problem with the electrical wiring or connections related to the SAIS system.

How is P0416 diagnosed?

If your vehicle’s MIL illuminates and displays trouble code P0416, the first step is to take it to a qualified mechanic or dealership for diagnosis. The technician will use a diagnostic scanner to read the code and determine the cause of the malfunction. They may also perform a visual inspection of the SAIS system and related components to check for physical damage or wear.

How is P0416 fixed?

Once the cause of the problem has been identified, the technician will recommend a course of action to fix it. Depending on the specific issue, this may involve replacing the SAIS switching valve B, repairing or replacing damaged vacuum lines, replacing the SAIS pump, or repairing faulty electrical connections. In some cases, a software update or reprogramming may also be necessary to ensure the SAIS system is functioning properly.


If you experience trouble code P0416 on your vehicle, don’t panic. While it can be concerning to see a MIL illuminated, this issue is typically fixable with the help of a trained professional. By understanding the basics of the SAIS system and the causes and solutions for this specific code, you can be better prepared to address the issue and get your vehicle back on the road.


  1. Can I still drive my vehicle if it has trouble code P0416?
    While it is possible to continue driving your vehicle with this code, it is not recommended. Driving with a malfunctioning SAIS system can cause increased emissions and harm the environment. Additionally, if left unresolved, the issue could potentially lead to more serious problems down the line.
  2. Can I fix P0416 myself?
    While some DIYers may attempt to fix this issue themselves, it is not recommended unless you have experience working on automotive electrical systems. This is a complex and potentially dangerous system, and a qualified technician is best equipped to diagnose and repair the problem.
  3. How much does it cost to fix P0416?
    The cost of fixing this issue will vary depending on the specific cause of the malfunction and the type of vehicle you own. In some cases, a simple repair such as replacing a vacuum line may cost a few hundred dollars. However, more complex repairs such as replacing the SAIS pump or switching valve B could cost upwards of $1,000.
  4. Can I prevent trouble code P0416 from occurring?
    While there is no guaranteed way to prevent this code from appearing, there are steps you can take to reduce the likelihood of a SAIS system malfunction. Regularly scheduled maintenance, including air filter replacements and fuel system cleanings, can help keep the system running smoothly.
  5. Is P0416 a serious issue?
    While this code is not a safety concern, it is still important to address it promptly to avoid potential damage to the SAIS system or other components of the vehicle. Additionally, driving with a malfunctioning SAIS system can harm the environment and result in increased emissions.