Volvo: OBD code PO410 on 98 S70, diagnostic scanners, orange arrow

Question
Which valve am I supposed to replace. The car is running fine except for the check engine and orange arrow flashing. I need to have the car smog checked before registering. Thanks

Answer
Igel,
The code indictes problems with the secondary air system [SAS] or the [PAIR] pulsed air system. So you need to find out what part is not working. Is it the air pump, the solenoid valve, the SAS valve or some broken vacuum lines. Best advice take it to some shop that has the diagnostic scanners and have a test made. Most times I find that the pump has seized and the SAS valve is stuck open. I have also found bad vacuum lines more than once.