I have an 1997 850 R Turbo. For the past month I have been hearing the sound of a vacuum or air leak. It sounds like it is coming from the front left. The check engine light came on and is pulling the code P0440, EVAP Emission Control system malfunction. I checked the gas tank cap and all the hoses, including the ones under the battery holder and the manifold hose. I couldn't find a leak. What would be the next step in finding out where the problem is? How can I diagnose if the problem is the air pump, the SAS valve or the cruise control pump? I don't think it is the cruise control pump b/c it is an emission problem. Is there something else it could be that I'm missing? Thanks for your help.

To check the air pump, lay down under the battery area and unplug the pump from the relay. You're looking for the connector with the blue wire as there are three plug ins to that relay if I remember. Take a jumper wire and put 12v on the pumps blue wire. If it runs, the pump is good. Your problem is then (1) THE RELAY (2) THE SAS valve or (3) the small selonoid located on the inside lip of the fan shroud with the purple and white vacuum lines running to it. The blower is the most $$$$$ of the 4 parts. Groton gets near $300. with the dealer getting $400.+ depending on how many more of his customers he wants to screw that week. I found a new pump on ebay for $150. but they're scarce. Check down the list of posts here. There is a fairly simple way to convert a VW pump to work on volvos and they're cheap like < $50.

Here's the site for the VW air pump conversion to volvo. Excellent site with detailed explanations and photos. Can save ya some serious $$$

http://www.matthewsvolvosite.com/air_pump_replacement_850.php

Thanks. I'll take a look at the site.

Purge Control Valve, or Canister Purge Valve...believe it's under the fuel rail which you'll have to take loose to get to.
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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.

Thanks. What are the symptoms if that valve is bad? Would I hear the sound of an air leak like I'm hearing from the front driver's side of my car?

I'd say there's a good chance of a "hissing" sound when under pressure. Replace the valve...not a bad repair, and clear your code and see if it comes back.
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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.