Understanding the Secondary Air Injection System

The original Plug and Play Bypass kit.

Have you ever wondered what keeps your Toyota SAIS emissions in check, especially when it’s cold outside? 

This important function is largely due to the Secondary Air Injection System (SAIS), a key component in your vehicle’s emission control strategy. 

Rutech Solutions discusses the secondary air injection system (SAIS), a crucial component in your vehicle’s emission control system that is designed to reduce emissions. 

What is a Secondary Air Injection System (SAIS)? 

The Secondary Air Injection System (SAIS) is a part of modern automotive emission control systems. When you start your car on a cold morning, the engine may not burn fuel as efficiently, leading to higher emissions. The SAIS addresses this issue by injecting fresh air into the exhaust stream, promoting the complete combustion of any unburned fuel. This process not only reduces harmful emissions but also enhances the overall efficiency of the engine. 

How Does the SAIS Work? 

Understanding the operation of the SAIS provides insight into its role in emission control: 

• Cold Start Phase: During the initial start-up, the secondary air pump activates, injecting hot fresh air into the catalytic converter improving its efficiency. 
• Promoting Combustion: This fresh air mixes with the exhaust gasses, facilitating additional combustion of leftover hydrocarbons and carbon monoxide. 
• Cleaner Emissions: The result is a significant reduction in emissions, making the vehicle more eco-friendly and compliant with emission standards. 

Why SAIS is Important for Emission Control 

The objective of the SAIS lies in its ability to reduce emissions during the critical cold start phase of engine operation. Without it, vehicles would emit higher levels of harmful gasses, particularly hydrocarbons and carbon monoxide. 

With more complete combustion, the SAIS helps vehicles meet stringent emission standards. 

Common Problems with SAIS 

Like all automotive systems, the SAIS can experience issues over time. Some common problems include: 

• Clogged Air Passages: Carbon buildup can obstruct the air passages and sensors, reducing system efficiency. 
• Faulty Secondary Air Pump: Electrical or mechanical failures in the pump can impair air injection and the deterioration of the SAIS. 
• Valve Problems: Malfunctioning valves can prevent proper air flow, leading to lip-mode and dash light associated with the SAIS.

Diagnosing SAIS Issues 

Diagnosing issues with the SAIS involves a combination of technology and inspection: 

• OBD-II Scanner: This tool reads diagnostic trouble codes from the vehicle's computer, providing clues to potential issues such as CEL codes P1441,P1442, 

P1443,P1445,P2440,P2441,P2441,P2443,P2444,P2445. 

• Visual Inspection: Checking for obvious signs of damage or disconnections in the system failed relays and fuse. 
• Sound Testing: listening to the vehicle at start up. Hearing a loud whining noise usually described as a loud vacuum cleaner will be the Air Injection pump/pumps failing. 

SAIS Maintenance Tips 

Proper maintenance is essential for the longevity and effectiveness of your SAIS: 

• Regular Checks: Inspect and listen to the air pump and valves for signs of wear or damage. 
• Prompt Repairs: Address any issues as soon as they are detected to avoid more extensive damage. 

Bypassing SAIS Components 

When repair or replacement is necessary, it is crucial to address the specific components involved: 

• Secondary Air Pump failure: Installing the bypass module and block off plates is a quick and cheap solution to resolving SAIS issues instead of needing to replace the AIR Injection pumps that cost upwards of $2000-$4000. 
• Switching Valve failures : Installing the bypass module and block off plates is a quick and cheap solution to resolving SAIS issues instead of needing to replace switching valves. Depending on the severity of the issue, valves may need to be cleaned or replaced due to a pressure sensor within the switching valve assembly to ensure proper airflow. 

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Keep Your SAIS Running Smoothly 

The SAIS is your car's first in line system to help control emissions at cold start up. Regular maintenance and timely repairs will keep any system on your vehicle working efficiently.