So we’ve decided to take the bitter pill. We have been dealt a P0411 secondary air injection malfunction. To understand what that means we’ll have to understand what the secondary air injection is and what it is meant to do when operating correctly.

Generic Scan Tool

We’re mostly familiar with the catalytic converter that has necessitated the use of unleaded gas since around 1975. 3-way catalytic converters break down hazardous carbon monoxide to harmless carbon dioxide. They also break down toxic hydrocarbons into carbon dioxide and water while reducing nitrogen oxides to regular nitrogen and oxygen.

For the Cat to do it’s job it has to be hot which can take a while. In order to meet strict emissions standards an air pump has been added to heat the Cat up sooner and reduce harmful emissions quicker. Pump air into the exhaust and it gets hot more quickly. When the Cat reaches 400 to 600 degrees Fahrenheit it begins to clean up the exhaust.

To let you know if the emissions system is working properly a number of self diagnostic regimens have been programmed into the engine management systems. One is a self test of the air injection or secondary air pump.

If that self test fails your check engine light illuminates and a P0411 diagnostic trouble code is stored in your engine management processor. In this case the processor is called DME.  Not a fun as MMI but DME serves it’s purpose.