Common Air Injection Check Valve Failures

One component you may not be familiar with is the air injection check valve. Vehicles that use a Secondary Air Injection (AIR) system to reduce tailpipe emissions have one or more of these valves. Learn here the common failures of the air injection check valve , and take your precautions against any possible damage.

Like any auto part, an AIR check valve can eventually fail, and when it does, you can experience a variety of problems. It is good that you know how to detect the error.

What is an air injection check valve?

To better understand air check valves, it helps to know how the air system works. As mentioned, not all vehicles have an AIR system, but those that do use the technology to reduce tailpipe emissions.

Depending on the vehicle, the AIR system may supply air to the exhaust manifolds, the catalytic converter, or both at different times. The additional air helps reduce harmful exhaust gases through oxidation. Also, the catalyst heats up faster when air is added to the exhaust manifolds.

Major components found in a typical AIR system include

• Air Pump (Electric or Engine Driven): Supplies air to the AIR system.

• Air Management Solenoids and Valves: Direct air to check valves and exhaust manifolds or catalytic converter. There may also be valves that direct air to the atmosphere.

• Check Valves: Prevent hot exhaust gases from collecting in the AIR system.

• Required piping (ie, hoses and tubes): Connects the various parts of the AIR system.

• Powertrain Control Module (PCM): Controls the air management solenoids and monitors the operation of the AIR system.

Normally, when the engine is cold, the PCM commands the air management solenoids to direct airflow to the exhaust manifolds. Once the engine warms up, the module commands solenoids to direct airflow to the catalytic converter.

There are also some systems that direct the airflow exclusively to the exhaust manifolds.

As for check valves, they usually work in response to airflow and back pressure from exhaust gases. Airflow from the AIR system will cause the check valve to open , while extreme exhaust back pressure (from backfiring, etc.) will force the valve closed.

Depending on the system design, there may be a single check valve or multiple check valves. Some check valves are exclusively passive devices, while others are operated by the PCM under certain conditions.

Common Air Injection Check Valve Symptoms and Failures

Not all vehicles have an AIR system, but those that do may experience problems with an AIR check valve (also known as an air injection check valve or air pump check valve).

Common bad air injection check valve symptoms and failures include:

1- Engine light illuminated

Your car’s main computer, often referred to as the Powertrain Control Module (PCM), oversees the operation of the AIR system . If the module detects a problem due to a bad check valve, it will turn on the check engine light and store a Diagnostic Trouble Code (DTC) in its memory.

Common DTCs related to air injection include P0410, P0411, all through P0419.

2- Increased tailpipe emissions

The main purpose of the AIR system is to reduce tailpipe emissions. A faulty AIR check valve can block airflow in the exhaust stream, hindering the performance of the AIR system and causing increased vehicle emissions.

3- Damage to other parts of the AIR system

A common air injection check valve failure can be when the valve prevents reverse exhaust flow from entering the AIR system. If the check valve fails, hot exhaust gases can re-enter the system , damaging components like the air pump and air management valves.