[thstone]

Those codes mean that the ECU is detecting a fault in the secondary air injection system. The SAI is used primarily at start up to reduce emissions when the engine typically runs fairly rich and the cat's may not be up to full operating temp. Use of the SAI leans out the exhaust gas for better emissions.

The basic idea is the ECU commands the secondary air pump to inject extra air into the exhaust gas and then monitors the pre-cat O2 sensors for the voltage to change (to the lean side). If there is no change as the extra air is being injected, then something is wrong with the system and the CEL is illuminated.

The possible failure list is long and their interaction can be somewhat complicated (because its a feedback loop it can be hard to determine where to start - kind of a chicken and egg problem - is the O2 sensor broke and sending out a constant voltage or is the air pump broke and not injecting any air resulting in a constant voltage at the O2 sensor! Or are both the O2 sensors and the air pump working fine but there is a leak or other problem somewhere in the plumbing? Ahhhh!!). This is why Soucorp's list of components to check is so extensive.

Hope this somewhat simplified explanation helps.