USP-S | Check Engine is a Mil-Spec-tier pistol finish, part of The 2018 Inferno Collection and dropped from the London 2018 Inferno Souvenir Package.

The float range for this finish is restricted to 0.00–0.60, so Factory New, Minimal Wear, Field-Tested, Well-Worn, and Battle-Scarred are the only obtainable conditions on the open market. The restricted range is set by Valve at the time of release.

A Souvenir version is available, dropped exclusively from cases collected during Major Championship matches and stamped with that tournament's stickers. Active listings for USP-S | Check Engine are tracked across 18 marketplaces, with prices spanning $0.67 to $105.84 depending on wear, variant, and seller.