How to fix a P0410 trouble code

The two most common causes of a P0410 trouble code

A P0410 code is a Secondary Air Injection System Malfunction. The two most common causes of causes of a P0410 are a bad switching valve or a bad A.I.R. pump. Here’s how to diagnose each and fix a P0410 trouble code,

What is secondary air injection?

On a cold start, the ECM commands a rich fuel mixture to help start the cold engine. Because the cold metal quenches some of the combustion early, un-burned fuel flows into the catalytic converter. The catalytic converter must reach a minimum temperature of around 500°F before it can begin burning off excess hydrocarbons. The catalytic converter needs the heat of the exhaust and oxygen to help it ‘light off.’

Carmakers use secondary air injection to blow more oxygen into the exhaust manifold to help it light off and reduce emissions during cold starts.

Secondary air does double duty by injecting outside air into the exhaust manifold. The oxygen in the outside air helps oxidize hot un-burned fuel entering the exhaust manifold and the extra oxygen helps the catalytic converter reach light off temperature earlier to reduce emissions.

How secondary air injection actually works

The system uses an air pump,, referred to as an Air Injection Reaction (A.I.R.) pump that blows outside air into the exhaust manifold. The A.I.R. pump can be an electric design or a belt driven pump.

Since you only want extra air during cold starts, the system also uses a solenoid operated diverter valve. The valve opens during secondary air operation and closes when the pump is off,

How the P0410 code sets

The ECM detects engine temperature from the engine coolant temperature sensor.

Electric Air Injection Reaction pump

On a cold start, the ECM powers the electric secondary air pump to run and powers the solenoid diverter valve to open and allow the outside air into the exhaust manifold or directly into the catalytic converter.

As the engine warms up, the upstream and downstream O2 sensors become active and the ECM monitors both sensors. It expects to see extra oxygen in the exhaust stream from the secondary air.

If it doesn’t see extra oxygen or doesn’t see enough, it’ll set a P0410 trouble code.

It’s easy to fix a P0410 code because it can only be caused by two components.

Secondary air one-way valve and solenoid

How to diagnose and fix a P0410 code

Using a multimeter, check for power and ground to the solenoid switching valve during a cold start. Or use a bi-directional scan tool to command the valve open. If you see power and ground but the valve doesn’t open, replace the valve. It’s a common failure part.

If you don’t see power and ground, check the wiring diagram for the location of the relay.

Use the same technique to test the A.I.R. pump. Check for power and ground. If you see that, the pump is bad and must be repalced.

©, 2023 Rick Muscoplat