Air Injection – Secondary Air Injection System – Types – Function – Failure

Air Injection - Secondary Air Injection System - Types - Function - Failure
Air Injection - Secondary Air Injection System - Types - Function - Failure

The secondary air injection system, is actually a component of the exhaust system.

Since no internal combustion engine is 100% efficient; there will always be some unburned fuel in the exhaust.

This increases hydrocarbon emissions.

As a result, the air injection system was created.

Combustion requires fuel, oxygen and heat. Without any one of the three; combustion cannot occur. Consequently, Inside the exhaust manifold there is sufficient heat to support combustion.

Secondary Air Injection System
Secondary Air Injection System

All we have to do is introduce some oxygen than any unburned fuel will ignite. The air injection smog pump pushes air into the exhaust system right after the exhaust manifold. Therefore, helping intercept and burn those unburned fuels.

The system is critical to help engines achieve government emissions standards.

This combustion will not produce any power; but it will reduce excessive hydrocarbon emissions.

Unlike in the combustion chamber; this combustion is uncontrolled. So, if the fuel content of the exhaust is excessive; explosions, that sound like popping, will occur. There are times when under normal conditions; such as deceleration, when the fuel content is excessive. So, Under these conditions we would want to shut off the air injection system. Adding a air injection diverter valve solves this problem. So, instead of shutting the air pump off; it diverts the air away from the exhaust manifold.

Diverter Valve
Diverter Valve

So, The air pump diverter valve allows air supplied from the air pump to be pumped; into the exhaust stream. Thus, reducing hydrocarbon and carbon monoxide tailpipe emissions. It functions as a one-way valve; allowing the air to pump through the exhaust. Therefore,  preventing the exhaust fumes from leaking back into the secondary air injection system. When the air pump diverter valve fails; it can lead to a variety of problems. In addition to a significant increase in the vehicle’s tailpipe emissions.

This is all done after the combustion process is completed. As a result, This device has no effect on engine performance.

Air Injection Systems Consist Of Mainly Two Different Designs:

Air Injection
Air Injection

Pump Type

  • The first system known as the Pump Type includes an air pump; commonly known as the smog pump. It is responsible for supplying fresh pressurized oxygen; to the exhaust stream through the exhaust manifold.

Pulse Type

  • The second type of system known as the Pulse Air System is much simpler. It relies on the vacuum created in the exhaust stream as it travels down the exhaust manifold.

A Failed Air Pump Will Produce A few Noticeable Symptoms:

  • Engine is running rough
  • Reduced horsepower
  • Check Engine Light comes on
  • Exhaust odor

P0410 Engine Code

What the P0410 code means.

P0410 is an OBD-II generic code that the engine control module (ECM) detected. The engine (O2) sensor did not detect an increase in the (O2) level in the exhaust; when the air injection system was activated.

What causes the P0410 code?

  • Low airflow into the exhaust.
  • The (O2) sensors are getting slow to respond to the increase in (O2) in the exhaust.
  • Excessive back pressure in the exhaust.
  • The air injection pump relay contacts not making contact.


A faulty pump is generally the most frequent cause of the system failing. Also, Too much moisture can cause damage which results in seizure of the pump. Faulty ground and voltage supply can also cause the pump to fail.

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