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 Brick 4 x 6 with 2 x 4 OpeningDark AzurePart 32531Element 6185546×3
Technic Plate 2 x 6 [5 Holes]Dark AzurePart 32001Element 6282116×4
Tile 1 x 8 with 1 to 8 Measuring Chart PrintDark AzurePart 4162pr0073Element 6299932×5
Torso, Hoodie with Zipper over Lime and Green Striped Shirt Print, Dark Azure Arms, Yellow HandsDark AzurePart 973c04h01pr3431Element 6153138×1
Dark Purple
27 pieces
Brick Curved 3 x 1 No StudsDark PurplePart 50950Element 6103449 or 4578772×2
Brick Curved 4 x 1 Double, No StudsDark PurplePart 93273Element 6069012×2
Brick Sloped 33° 3 x 2Dark PurplePart 3298Element 6055875 or 4224864×2
Plate Round 1 x 1 with Solid StudDark PurplePart 6141Element 4566522×6
Plate Round 2 x 2 with Axle Hole Type 1 (+ Opening)Dark PurplePart 4032aElement 6030534×4
Plate Special 2 x 2 Splat Gear, 6 TeethDark PurplePart 35442Element 6238330×3
Tile 1 x 2 with GrooveDark PurplePart 3069bElement 4613192×4
Tile 2 x 4 with GrooveDark PurplePart 87079Element 6167472×4
Lime
26 pieces
Brick Sloped 65° 2 x 2 x 2 with Bottom TubeLimePart 3678bElement 6251847 or 4212627×4
Plate 2 x 4LimePart 3020Element 4537936 or 4534667×2
Plate 6 x 6LimePart 3958Element 4525858×2
Plate Special 1 x 2 with 1 Stud with Groove and Inside Stud Holder (Jumper)LimePart 15573Element 6092592×6
Plate Special 6 x 6 Splat Gear, 14 TeethLimePart 35446Element 6302509×2
Technic Brick 1 x 16 [15 Pin Holes]LimePart 3703Element 6132379×6
Technic Brick 1 x 4 [3 Pin Holes]LimePart 3701Element 6132373 or 4166527×4
Medium Azure
21 pieces
Brick 1 x 4Medium AzurePart 3010Element 6603319 or 6036238×2
Brick Sloped 45° 2 x 2Medium AzurePart 3039Element 6173655×2
Plate Special 4 x 4 Splat Gear, 10 TeethMedium AzurePart 35443Element 6238331×5
Sports Ski 6LMedium AzurePart 90509Element 6170544 or 6088558×2
Tile 1 x 4 with GrooveMedium AzurePart 2431Element 4624705×2
Tile 2 x 2 with GrooveMedium AzurePart 3068bElement 6060857×8
Tan
19 pieces
Technic Axle Pin without Friction Ridges LengthwiseTanPart 3749Element 4666579 or 4186017×8
Technic Gear 20 Tooth Double Bevel with Axle Hole Type 1 [+ Opening]TanPart 18575Element 6346517 or 6084724×3
Technic Pin Long without Friction Ridges, with Anti-Roll NotchTanPart 39888Element 6321305×6
Tile Round 2 x 2 with Pepperoni Pizza PrintTanPart 14769pr1070Element 6174830×2
Bright Green
16 pieces
Technic Beam 1 x 7 ThickBright GreenPart 32524Element 6097392×4
Technic Pin Connector Round [Slotted]Bright GreenPart 62462Element 6173135 or 6097400×4
Technic Plate 2 x 8 [7 Holes]Bright GreenPart 3738Element 6138494×8
Dark Bluish Gray
3 pieces
Hips and Dark Bluish Gray LegsDark Bluish GrayPart 970c12Element 6168713 or 4570433×1
Wheel Centre Small with Stub Axles (Pulley Wheel)Dark Bluish GrayPart 3464Element 6005463×2
Light Aqua
2 pieces
Brick Special 1 x 2 x 2 with Photo ClipLight AquaPart 37452Element 6290244×2
Pearl Gold
2 pieces
Equipment Trophy Cup SmallPearl GoldPart 10172Element 6181575 or 6100303×2
Sand Green
2 pieces
Bar 3L with Handle, Stop Ring and Side Stops (Minifig Ski Pole)Sand GreenPart 90540Element 6233298×2
Dark Turquoise
1 piece
Brick and Axle Separator v2.0Dark TurquoisePart 96874Element 6254100×1
Flat Silver
1 piece
Tool Screwdriver and Spanner / WrenchFlat SilverPart 4006Element 6167576×1
Medium Nougat
1 piece
Animal, Dog, Alsatian / German Shepherd (Police Dog) with Black Eyes and Forehead PrintMedium NougatPart 92586pr0001Element 4614195×1
Trans-Light Blue
1 piece
Windscreen 2 x 4 x 2Trans-Light BluePart 3823Element 6581802 or 6253682×1
[No Color/Any Color]
1 piece
Sticker Sheet for Set 45401-1[No Color/Any Color]Part 67969Element 6300581×1
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.