IIRC is one of the 1st signs of the banjo filler bolt getting plunged. Pull both bolts, inspect. And go from there. One in front DS head & the 2nd, rear PS the feed the turbo. If clean, the AVCS need a good cleaning or replaced.
Still rocking the Original Motor & VF-40 Turbo with 15k OCI. Member of the 200K + club. Currant mileage:234455