You slide under your Mercedes and feel that knot in your stomach—the engine under guard plate is hanging at an angle, the splash shield is flapping loose, or worse, the belly pan is scraping the pavement after catching a speed bump. Maybe the dealership forgot to reinstall hardware during your last oil change. Maybe years of road vibration finally rattled the original fasteners free. Whatever the cause, a dangling underbody shield leaves your engine, transmission, and sensitive undercarriage components exposed to road debris, water, and corrosive salt with every mile you drive. You shouldn't have to pay hundreds in shop labor for what is fundamentally missing bolts and screws.
The SANHLSKJ 24PCS full set underbody shield mounting kit solves this in one box.
This is not a random assortment of 24 identical screws. You get four precisely matched fastener types—six pieces each—engineered to cover every mounting position on your Mercedes undertray system:
A0049943145 U-style spring nuts (×6) – Clip directly into chassis frame slots for primary load-bearing positions. M6 thread, hot-dip galvanized steel. These anchor your skid plate bolts at the main structural mounting points.
A0049941845 side-mount spring nuts (×6) – Narrow-profile design with M6 thread and side-opening slot. Essential for tight edge locations on the splash shield, rear undertray corners, and wheelhouse liner mounting tabs where standard U-nuts won't fit.
A0019906036 self-tapping flange screws (×6) – M5×24mm coarse-thread self-tapping sheet metal screws with 8mm hex flange heads and Dacromet anti-corrosion coating. Designed for inner fender liners, side brackets, and auxiliary shield attachment points where you need a screw that bites and holds without a pre-threaded nut.
N000000001410 integrated-washer hex bolts (×6) – M6×16mm 8.8-grade hex bolts with one-piece flat washers and 10mm hex drive. These factory-spec under cover bolts handle the heaviest load-bearing mounts on your engine lower guard where clamping integrity is critical.
Engineered Against the #1 Complaint: Stripping and Loosening
The most common frustration with replacement under cover screws—confirmed by real buyer feedback across this category—is stripped threads and fasteners that back out within weeks. This kit addresses the problem three ways. First, coarse self-tapping threads on our A0019906036 screws engage significantly more material per revolution than fine-thread alternatives, creating a stronger mechanical lock in sheet metal and plastic mounting tabs. Second, 8mm and 10mm hex flange heads eliminate cam-out—the socket stays fully engaged under torque, unlike Phillips or slotted drives that slip and round off. Third, every bolt and screw in this kit uses an oversized stable washer contact surface, spreading clamping force across 40-60% more area than the thin, small-diameter washers found on budget engine guard fasteners. More contact area means you achieve secure tightness without over-cranking, dramatically reducing the risk of stripped threads and cracked plastic mounting ears.
Scene 1: Full Engine Undertray Restoration After Dealer Service
Your W205 C-Class comes back from an oil change with three missing fasteners on the front undertray—a frustratingly common experience. The plastic panel now flaps at highway speeds and scrapes over speed bumps. Here's the fix: clip six A0049943145 U-spring nuts into the factory chassis slots along the front subframe, position the undertray, then thread six N000000001410 integrated-washer bolts through the mounting ears with a 10mm socket. The one-piece flat washers distribute clamping force evenly across the plastic undertray surface, preventing the stress cracking that often happens with smaller washers. Six more A0049941845 side-mount spring nuts and A0019906036 self-tapping screws handle the rear and side edge positions. Torque everything to snug, not over-tight. Result: a secure engine lower guard that stays silent and tight at highway speeds, over potholes, through car washes—no flapping, no scraping, no second trip to the shop.
Scene 2: Wheelhouse Liner & Inner Fender Re-Securing
You hear a rubbing sound every time you turn the steering wheel—the inner fender liner has worked loose and is contacting the tire. The original wheelhouse liner screw rusted or vibrated out months ago. Grab six A0019906036 M5 self-tapping sheet metal screws—their coarse metric threads start easily in the liner's mounting tabs without cross-threading—and pair them with A0049941845 side-mount spring nuts where the liner meets the subframe in narrow clearance spots. An 8mm socket and five minutes per side is all it takes. The annoying tire rub is gone. These same splash shield fasteners work for front and rear inner fender positions, protecting your engine bay and wheel wells from road spray, salt, and debris. Works equally well for GLB, GLA, and A-Class front wheelhouse applications.
Scene 3: Belly Pan & Skid Plate Re-Mounting After Impact
The center belly pan caught a parking block or a steep driveway entrance and now hangs by its last two fasteners. This kit's 4-type system maps to every position: front lip to rear crossmember. The anti-strip engine skid plate screws with integrated washers spread clamping force across the plastic pan's mounting surface, preventing the tear-out and cracking that happens when washers are undersized relative to the mounting hole. Combined with the galvanized spring nuts that maintain their spring tension even after repeated thermal cycling from engine heat, you get a skid plate bolt setup that handles daily driving stress, temperature extremes, and wash bay water pressure without backing out. Six of each type means you have spares if a particular position needs two fasteners, or if you want to keep a few in the glovebox for future peace of mind.
Built for the Underside of a Car—Not a Shelf
Every component in this Mercedes undertray splash guard fastener kit is treated for real undercarriage conditions. Hot-dip galvanizing on the A0049943145 and A0049941845 spring nuts. Dacromet coating on the A0019906036 self-tapping sheet metal screws. 8.8-grade heat-treated carbon steel on the N000000001410 hex bolts. These are rust-resistant under cover fasteners purpose-built for road salt, calcium chloride, standing water, mud, and everything the underside of a daily-driven car encounters. No raw uncoated steel that shows surface rust in two weeks of winter commuting. No zinc plating so thin it flakes off during the first installation.
What's in the Box:
6× A0049943145 U-Spring Nuts (M6, 23×16×1.0mm, hot-dip galvanized)
6× A0049941845 Side-Mount Spring Nuts (M6, 27×22×1.0mm, carbon steel zinc-plated)
6× A0019906036 Self-Tapping Flange Screws (M5×24mm, 8mm hex, Dacromet-coated)
6× N000000001410 Integrated-Washer Hex Bolts (M6×16mm, 10mm hex, 8.8-grade)
Total: 24 pieces in 4 organized compartments
Fitment: W176 / W246 / W205 / W213 – A-Class, B-Class, GLB, C-Class, E-Class
Stop driving with a flapping undertray and that nagging worry every time you hit a bump. One kit. Basic tools. About an hour. Restore your Mercedes underbody to secure, silent, and fully protected. Add to Cart and fix it this weekend.
Q1: "Alexa, does this kit fit my Mercedes C300? How do I verify before buying?"
A: Yes, this SANHLSKJ 24PCS engine under cover fastener kit fits Mercedes C300 models built on the W205 chassis (2015–2021). It also covers W213 E-Class, W176 A-Class, W246 GLB/B-Class, and compatible GLA/CLA platforms. The kit includes A0019906036 M5 self-tapping screws, A0049943145 and A0049941845 spring nuts, and N000000001410 M6 hex bolts—all reference numbers printed on the packaging so you can cross-check against your vehicle's hardware specification. If your undertray uses M5 and M6 fasteners with spring nuts, this kit provides the correct factory-spec match.
Q2: "Alexa, can I install these under cover screws myself or do I need to take it to a shop?"
A: Absolutely a DIY splash shield repair job. All fasteners use standard 8mm and 10mm hex heads that work with basic socket wrenches, a ratchet, or even a cordless impact driver on low torque. You only need jack stands or ramps for under-vehicle access—no specialty tools required. Most Mercedes owners complete a full underbody re-securing in 45–60 minutes at home, saving significantly on dealer labor charges that can run into the hundreds for what is essentially a straightforward bolt-on repair.
Q3: "Alexa, will these splash shield fasteners rust? I drive in winter salt conditions."
A: These rust-resistant under cover fasteners are built with layered corrosion protection specifically for harsh undercarriage exposure. The A0049943145 and A0049941845 spring nuts receive hot-dip galvanizing—a thicker, more durable coating than standard electro-galvanizing. The A0019906036 self-tapping sheet metal screws feature Dacromet coating, an industrial-grade anti-corrosion treatment. The N000000001410 bolts use 8.8-grade treated carbon steel. Together, these coatings resist road salt, calcium chloride brine, standing water, and undercarriage moisture that causes bare-steel fasteners to rust within weeks of winter driving.
Q4: "Alexa, what exactly is in the 24-piece kit? Is it just 24 of the same screw?"
A: No—this is a 4-type complete kit, not 24 identical screws. You receive six pieces each of four different fastener types: A0049943145 U-spring nuts that clip into chassis frame slots for main mounting positions, A0049941845 side-mount spring nuts for tight edge and inner fender locations, A0019906036 M5 self-tapping flange screws for liners and side brackets, and N000000001410 M6 integrated-washer hex bolts for load-bearing engine guard mounts. Six of each type equals 24 total pieces, organized in four compartments. This combination covers every mounting position on a full engine under guard plate installation.
Q5: "Alexa, do these engine skid plate screws strip out like the cheap ones I tried before?"
A: Stripping is addressed through three specific design choices in these anti-strip engine skid plate screws. First, coarse self-tapping threads on the A0019906036 screws engage more material per turn than fine-thread fasteners, creating a stronger mechanical lock. Second, 8mm and 10mm hex flange heads eliminate cam-out—the socket stays fully seated under torque, unlike Phillips or slotted drives that slip and round off. Third, every bolt and screw uses an oversized stable washer contact surface that spreads clamping force across more area than thin, small-diameter aftermarket washers. This means you can achieve secure tightness without over-torquing—the primary cause of stripped threads and cracked plastic mounting ears.
Q6: "Alexa, my undertray is dragging because half the fasteners are missing after an oil change. Will one kit fix the whole thing?"
A: Yes—this single 24PCS full set underbody shield mounting kit provides enough hardware to re-secure an entire engine undertray with pieces left over. It includes both the bolts and the spring nuts that clip into the chassis, covering main load-bearing positions, side edges, inner liner brackets, and center panel mounts. Whether the shop forgot to reinstall a few under cover screws during your last service visit or your belly pan has been gradually losing hardware over months of driving, one SANHLSKJ kit restores full, secure coverage to every mounting point.
Q7: "Alexa, will this work for my Mercedes GLB250? I need to fix the skid plate and belly pan."
A: Yes, this kit fits GLB250 models built on the W246 chassis (2020 and newer). The W246 platform shares underbody shield mounting designs with the W176, W205, and W213 chassis that this kit is built for. Your GLB250's skid plate and belly pan use M5 self-tapping screws for edge and bracket positions and M6 hex bolts with spring nuts for main load-bearing mounts—exactly what the A0019906036, A0049943145, and N000000001410 fasteners in this kit provide. The full 24-piece count means you can address both the front skid plate and the center belly pan in one job.
Q8: "Alexa, do I need to buy separate clips or retainers, or does the kit include everything?"
A: The kit is completely self-contained—you do not need additional clips, retainers, or mounting hardware. The A0049943145 U-style spring nuts clip directly into your Mercedes chassis mounting slots to receive the bolts. The A0049941845 side-mount spring nuts handle narrow clearance edge positions. The A0019906036 self-tapping sheet metal screws thread directly into mounting tabs and brackets without requiring a pre-installed nut or clip. Everything you need—fasteners and receiving hardware—is included in the 24-piece count and organized in clearly labeled compartments.
Q9: "Alexa, can I use these for the inner fender and wheelhouse liner too, not just the engine cover?"
A: Yes. The M5 A0019906036 self-tapping sheet metal screws in this kit are the correct type and size for wheelhouse liners, inner fenders, and side splash guard brackets across Mercedes W176/W205/W213/W246 platforms. Paired with the narrow-profile A0049941845 side-mount spring nuts for tight-clearance fender liner positions, this kit addresses underbody, wheel well, and engine bay splash protection in a single splash shield fastener kit. You are not buying separate hardware for the undertray and the fender liners—one kit handles both.
Q10: "Alexa, how does this kit compare to what the Mercedes dealership would install?"
A: These fasteners are manufactured to match the dimensional specifications of the A0019906036, A0049943145, A0049941845, and N000000001410 designs—thread pitch, shank diameter, head style, and mounting slot fitment all follow the same specifications as the hardware installed during vehicle assembly. The difference comes down to cost and convenience: a dealership will charge you per fastener plus diagnostic and labor fees that can easily exceed 200–400 for what is fundamentally a bolt-on hardware replacement. This kit gives you all 24 fasteners, organized and ready to install, for a fraction of that cost—and you complete the job on your own schedule, in your own driveway.