Genuine Mazda Windscreen Cowl Screw Grommet & Seal • BJ0J-50-798

Genuine Mazda BJ0J-50-798 Windscreen Cowl Screw Grommet & Seal

Replacement Genuine Mazda windscreen cowl screw grommet for all Mazda MX-5 Mk3, Mk3.5 and Mk3.75 NC models produced from 2005 to 2015.

The grommet fits into the body beneath the plastic windscreen cowl grille and receives the cowl-cover retaining screw. Its integral sealing gasket closes the mounting hole and helps prevent rainwater passing into the vehicle.

The original gasket can flatten, split or deteriorate with age. Once the seal has broken down, rainwater may travel through the cowl mounting hole and enter the driver or passenger footwell.

One grommet is fitted on each side of the vehicle. Two are required per MX-5, while this listing supplies one Genuine Mazda grommet. Select a quantity of two when replacing both sides.

The visible cowl screw cover or cap is a separate component and is not included unless specifically stated.

• Part type: Windscreen cowl screw grommet
• Common names: Scuttle-panel grommet / cowl grille grommet / screw insert
• Mazda catalogue description: Screw, Grommet
• Location: Beneath the windscreen cowl grille
• Position: Left- or right-hand side
• Handed component: No
• Function: Receives the cowl retaining screw and seals the body aperture
• Integral sealing gasket: Yes
• Quantity fitted per vehicle: 2
• Quantity supplied: 1 grommet
• Cowl retaining screw included: No
• Visible screw cap included: No
• Cowl grille included: No
• Brand: Genuine Mazda
• Part No.: BJ0J-50-798
• MX-5 fitment: Mk3, Mk3.5 and Mk3.75 NC models

Possible signs of a failed cowl grommet seal:

• Water entering the driver or passenger footwell
• Damp carpet after rainfall or washing
• Condensation or musty odours inside the cabin
• Water staining below the windscreen cowl area
• Integral gasket cracked, flattened or missing
• Grommet loose within the body aperture
• Cowl retaining screw no longer holding securely

Fitment advice: This grommet fits either side of the original windscreen cowl grille used throughout the MX-5 NC range. Two identical grommets are used per vehicle.

Leak diagnosis: A deteriorated cowl grommet is a common source of footwell water ingress, but the surrounding cowl panel, drain paths, windscreen bonding and other body seals should also be inspected where moisture remains after replacement.

Other items to consider: Inspect the grommet on the opposite side, both cowl screw covers, the retaining screws, plastic cowl grille and surrounding drainage channels. Consider replacing both grommets together where they are the same age.

Useful tools / consumables: Plastic trim-removal tool, suitable screwdriver, cleaning cloths and a mild body-safe cleaner for the mounting area.

Difficulty guide: DIY Difficulty: Easy. Access requires removal of the visible screw cover and retaining screw before lifting the relevant section of the cowl grille.

Why Genuine Mazda? Genuine Mazda cowl grommets match the original body aperture, retaining-screw thread and sealing-gasket profile. Correct dimensions help secure the cowl grille while providing the intended seal against rainwater.

What’s in the box: One Genuine Mazda windscreen cowl screw grommet with integral sealing gasket, part number BJ0J-50-798.

Installation notes: Protect the surrounding paint and plastic trim before removing the cowl screw cover and retaining screw. Lift the cowl grille sufficiently to access the original grommet, then remove it without enlarging or damaging the body aperture. Clean and dry the mounting surface thoroughly. Press the replacement grommet fully into the aperture so its sealing flange sits evenly against the body. Refit the cowl grille and screw without overtightening, then replace the visible cap. Repeat on the opposite side where replacing both grommets and test the area carefully for water ingress.