Cleared your cats or installed a downpipe and now fighting a check engine light? RVNG O2 Spacers move the rear oxygen sensor slightly out of the direct exhaust stream so its readings stay in range and the CEL stays off. Each spacer is inspected for defects before shipping.They work 100% of the time on twin-turbo vehicles and about 85% of the time on single-turbo cars — on some single-turbo setups a code can still appear depending on the tune.Effectiveness Twin-turbo vehicles — effective in essentially all cases Single-turbo vehicles — effective in roughly 85% of cases Emissions disclaimer: This product is not legal for sale or use on pollution-controlled vehicles operated on public roads and is intended for off-road, race, or closed-course competition use only. You are responsible for compliance with all applicable emissions laws; use on public roads may violate the Federal Clean Air Act (42 U.S.C. § 7522) and similar state laws. Please check your local laws before purchase and installation.Ships from our Vancouver shop — KORE SPEED is proudly Canadian-owned, with no surprise cross-border duties for Canadian buyers. Questions on fitment? Email [email protected].