Rule out the usual hiding places first. If the piece really is gone, check the set piece by piece
and leave with the element ID LEGO asks for, or a link to buy the part.
Technic Gear 12 Tooth BevelTanPart 6589Element 4565452 or 4514556×4
Tiles
7 pieces
Tile 1 x 2 with GrooveBlackPart 3069bElement 306926×1
Tile 1 x 3BlackPart 63864Element 4558170×1
Tile 1 x 4 with GrooveBlackPart 2431Element 243126×2
Tile 1 x 6 with GrooveBlackPart 6636Element 663626×1
Tile 2 x 6BlackPart 69729Element 6318582×2
Bricks Curved
6 pieces
Brick Curved 2 x 1 No Studs [1/2 Bow]BlackPart 11477Element 6047276×2
Brick Curved 3 x 1 No StudsBlackPart 50950Element 4251161×2
Brick Curved 3 x 1 No StudsLimePart 50950Element 4537928×2
Bars, Ladders and Fences
5 pieces
Bar 4L (Lightsaber Blade / Wand)BlackPart 30374Element 6116604 or 4140303×2
Bar 4L (Lightsaber Blade / Wand)LimePart 30374Element 6327442×3
Flags, Banners and Signs
4 pieces
Flag 2 x 2 Trapezoid with Flared Area between ClipsBlackPart 80324Element 6363033×2
Flag 2 x 2 Trapezoid with Flared Area between ClipsLimePart 80324Element 6454589×2
Technic Special
4 pieces
Technic Tooth 1 x 3 with Axle Hole [Hollow Underside]LimePart 48267Element 6322197×4
Plates Special
3 pieces
Plate Special 1 x 2 with Pin Hole on TopBlackPart 11458Element 6114987×2
Plate Special 2 x 2 with 2 PinsDark Bluish GrayPart 15092Element 6284702 or 6066952×1
Technic Bricks
2 pieces
Technic Brick 1 x 2 [2 Pin Holes]BlackPart 32000Element 3200026×2
Tubes and Hoses
2 pieces
Axle Hose, Soft 16LLimePart 32202Element 6303399 or 6149976×2
Stickers
1 piece
Sticker Sheet for Set 42161-1[No Color/Any Color]Part 10101063Element 6415928×1
Technic Beams Special
1 piece
Technic Beam 3 x 0.5 Liftarm with Boss and Blocked, Squared Pin HoleRedPart 61408Element 6331864×1
Technic Steering, Suspension and Engine
1 piece
Technic Steering Wheel Small (3 Studs Diameter)BlackPart 2819Element 4580509 or 4160709×1
Tiles Round and Curved
1 piece
Tile Round 1 x 1 with Lamborghini Symbol PrintBlackPart 98138pr0161Element 63236351 spare in the box×1
Tick each piece as you find it, or mark it missing.
When a piece really is missing
Ask LEGO
LEGO takes requests for pieces missing from a new set through its customer service site. The form asks for
the set number and each piece's element ID, the number printed beside the piece in the parts list at the back
of the instructions. This checker lists both.
Mark a piece missing and your list links it to an eBay search for that part, which also covers pieces from
older or second-hand sets.
Keep a record
Copy or download your missing list (the CSV opens in any spreadsheet), or print the whole checklist and tick
pieces off on paper. Your marks stay in this browser, so you can check a big set over several sittings.