Secondary air injection is a simple system that blows air into the exhaust to eliminate the rich smell when started cold or warm. Better said, it lowers emissions. When the SAI system fails, the check engine light comes on, and a diagnostic trouble code is stored in the engine computer.
The system has a combi valve that operates using vacuum to pass air into the exhaust system. As the vacuum hoses get old, hose failure becomes the most common cause of SAI system failure. Sometimes the combi valve springs a leak or gets stuck. Or the blower motor that supplies the air fails. The worst and thankfully rarest possibility is that the passageways for the air get filled with carbon in the section where the air mixes with exhaust. It is perhaps worth mentioning that these carbon deposits are just another consequence of using inferior quality fuel.
After the code for secondary air injection failure is confirmed, the technician proceeds to diagnose the system to reveal the cause of failure. For each engine and model, and including the appropriate repair, the total cost can vary. But most failures are due to vacuum hoses, and take 1 to 2 hours to diagnose and repair. Other possible causes can take 3 to 4 hours. Only the clogged exhaust port issue can take longer. Karmakanix technicians always sort it out efficiently, not just because of training, but that we have seen pretty much every way the problem can happen. We can say that for sure it will cost less to repair it at Karmakanix than at any dealership.