My son's 97 850 T5 (turbo) has shown a (generic) CEL code of PO172 which cross references to Volvo code EFI 231 or 232 (fuel trim). Any suggestions on where to start would be appreciated. (O2 sensors seem to be ok- my tool captures live data).

Many thanks

 

Every time I have had that code I have found a vacuum line loose from my PTC valve. It's part of the PCV system close to the turbo. Check the line to make sure it's connected and the elbow for a tear.

Item 10 closest to 8 on this pic.
http://www.fcpgroton.com/product-exe...category_id/63

 

Thanks for the reply, esp. the link to the parts diagram. All the vac. lines and fittings have been replaced within the past year to avoid these types of issues. Checked the fitting you indicated (good, new) as well as all the other vac, hoses/fittings. Did find one hose that seemed a little loose, replaced that, cleared the code, and crossed my fingers. Within a day and approx. 100 miles it was back. Back to the drawing board. Again, thanks.

 

172 is almost always a vac issue like rspi said...
did you check the elbows on the manifold and at the pressure regulator?


After a quick google search for some pics, I found this for reference....

 

Any driveability issues?

 

I know the original post is now a month old, but I want to thank Matty XXL for the tip. The elbow referenced in your link was completely shot. Replaced it, cleared the code, car passed emissions! Many thanks