my 1998 V70has a CEL error #P0410 Secondary Air Injection System Malfunction. it seems that my gas mileage is bad. Any ideas where or what to start checking. Thanks in advance. bobd

Welcome to the wonderful world of SAS related codes! I hope you enjoy your experience. It's bound to fail eventually. I'm typing about the secondary injection pump. Mine is dripping water through the cracks a failed SAS check valve is often the culprit. The valve leaks and lets water into the system and where does gravity take water? Down, did you say? That's right! The water settles in the pump thereby rendering the pump bad so now you have two parts to replace. Thank you Volvo! My $400 bill from www.fcpgroton.com is steep but not near as steep as the dealer or anyone else for that matter.
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98 XC 120k 83 245 DL 170k Oh yeah, and a 96 Neon

so far i have removed the secondary air pump and it is completely dry and tested fine when 12 volts was applied, i have replaced several vacuum hoses including the one to secondary air valve attached to the ex-manifold. I have also replaced lines at the flex hose from air cleaner to the throttle body, on the back side of this hose there appears to be a modern version of the flame trap with 2 lines coming to it, 1 about 1/8" and the other about 1/4", i replaced both of these. since i had disconnected the battery to doo all of this, it reset the CEL, since 01/01/2006 no new codes have appeared, who knows maybe it was just vacuum lines, but i cant hear the pump run when cold

Have you replaced the SAS valve? That may be the culprit to begin with. It's up above the turbo at the back of your engine. It looks like this:
http://www.fcpgroton.com/volvo850fuelsystem.htm
You can order it here: http://www.fcpgroton.com/volvo850fuelsystem.htm
Also known as the air pump check valve.
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon. My cars have been running so well lately they've got me worried.

A site to head to: www.obd-codes.com
good luck