Originally Posted by Jaypod
I *think* the secondary air pump is only used for cold starts to provide fresh air to the cats. Not sure what would cause it to fail other than it being an electric part which would no doubt fail eventually.
Correct, sends O2 into the exhaust stream on a cold start (rich condition) to help burn off excess hydrocarbons (unburned fuel). In it's location above the engine it is exposed to some pretty high temps, so yeah...
Back on topic!