As noted, there is no flame trap. However, there will a nipple / valve where the tube from the crankcase and oil separator connect to the air intake. That is where the fumes get sucked through and back into the combustion process. Unlikely that your separator box is plugged at such low mileage, but cleaning the valve is most critical every 30k or so. It has a very small hole that gets plugged, and that backs up the whole system (all of this is in the pre-01 turbo's, but I'm pretty sure it must be replicated in the '01 on but I haven't explored ours yet). On the older version, this valve is almost hidden down at the end of the air intake tube from air box to turbo inlet (has a couple of small tubes and an electrical connection on it). If nothing else, go to that air intake tube, and follow it all the way to the intake at the turbo itself. should be along there somewhere, maybe even more accessible if Volvo bothered to help maintenance when they re-did the routings of some of those tubes.
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Mike Sullivan '07 XC70, '95 855T (100k), '95 855 NA (148k). Past Volvo's: '85 744 (256k), '86 245 (165k), '86 245 (195k), '88 745 (208k), '91 745 (196k), '93 965 (147k) , '98 V70XC (98k).