Genuine Mazda Rear Combination Lamp Flange Nut – MX-5 All Models • 9994-00-503

Genuine Mazda 9994-00-503 Rear Combination Lamp Flange Nut

Replacement Genuine Mazda flanged retaining nut for Mazda MX-5 Mk1 / NA, Mk2 and Mk2.5 / NB, Mk3 / NC, and Mk4 / ND and RF rear combination lamps listed in the compatibility table.

The nut threads onto a mounting stud on the rear lamp assembly from inside the luggage compartment or rear body area.

Its integral flange spreads the clamping load around the mounting point while holding the lamp securely against the vehicle body and lamp-to-body gasket.

Replacement may be required where an original nut is missing, corroded, seized, rounded, cross-threaded or damaged during rear-lamp removal.

This listing supplies one individual Genuine Mazda retaining nut. Multiple nuts may be fitted to each rear lamp depending on the vehicle generation and lamp design.

• Part type: Flanged retaining nut
• Mazda catalogue description: Nut, flange
• Alternative descriptions: Tail-lamp nut / rear-light nut / combination-lamp retaining nut
• Primary function: Secures the rear combination lamp to the vehicle body
• System: Rear exterior lighting and body fittings
• Fitting position: Rear lamp mounting studs
• Vehicle application: Mazda MX-5 Mk1 / NA through Mk4 / ND and RF
• Thread size: M5
• Typical hex size: 10 mm
• Fastener type: Flanged nut
• Quantity supplied: One individual nut
• Quantity required: Depends on lamp assembly and vehicle generation
• Brand: Genuine Mazda
• Part No.: 9994-00-503
• Also referenced as: 999400503 and 99940-0503

Typical reasons for replacement:

• Rear combination lamp removed for replacement or body repair
• Original retaining nut missing
• Nut corroded or seized onto the lamp stud
• Hexagon rounded during removal
• Internal thread damaged or cross-threaded
• Flange distorted or cracked
• Incorrect non-original fastener previously fitted
• Lamp loose or inadequately secured

Fitment advice: This fastener is used on the rear combination-lamp mountings across Mazda MX-5 Mk1, Mk2, Mk2.5, Mk3 and Mk4 models. The number of nuts required varies according to the lamp and vehicle generation.

Quantity advice: This listing is for one nut. Count the mounting studs on the relevant lamp or retain the original hardware as a reference before ordering the full quantity required.

Thread advice: Start the nut by hand and confirm that it turns freely. Do not force it onto a damaged, contaminated or cross-threaded lamp stud.

Gasket advice: Inspect the lamp-to-body gasket whenever the lamp is removed. A compressed, torn or incorrectly seated gasket may allow water into the luggage compartment even when the retaining nuts are secure.

Tightening advice: Tighten the lamp nuts evenly and only sufficiently to secure and seal the assembly. Excessive tightening can crack the plastic lamp housing, damage the mounting stud or distort the body gasket.

Corrosion advice: Clean loose corrosion from the mounting area and inspect the lamp studs before installing new hardware. Replace the lamp assembly if a mounting stud is fractured or severely corroded.

Water-leak advice: Where the lamp is being removed to investigate a luggage-compartment water leak, inspect the gasket, body aperture, drainage channels and surrounding seams before reassembly.

Other items to consider: Consider inspecting the remaining lamp nuts, lamp-to-body gasket, wiring connector and luggage-compartment trim clips during the same repair.

Useful tools / consumables: 10 mm socket, small ratchet, trim-removal tools, penetrating fluid where required and clean lint-free cloths.

Difficulty guide: DIY Difficulty: Easy to moderate. Access normally requires removal or repositioning of luggage-compartment trim, followed by careful tightening to avoid damaging the lamp.

Why Genuine Mazda? Genuine Mazda lamp fasteners are manufactured to the intended thread size, flange dimensions and clamping arrangement. Using the correct OE nut helps secure the lamp without substituting an unsuitable fastener that may damage its mounting stud or housing.

What’s in the box: One Genuine Mazda M5 flanged rear combination-lamp retaining nut, part number 9994-00-503. Rear lamp, gasket, additional nuts and installation tools are not included unless specifically shown or stated separately.

Installation notes: Switch off the vehicle lighting and gain access to the rear of the lamp through the luggage-compartment trim. Check that the lamp and gasket are correctly positioned, then start the nut onto the mounting stud by hand. Tighten the lamp fasteners evenly without overtightening. Refit the trim and test all lamp functions before returning the vehicle to service.