Genuine Mazda Rear Exhaust Back Box Heat Shield – MX-5 Mk1 / NA • NA01-56-451

Genuine Mazda NA01-56-451 Rear Exhaust Back Box Heat Shield

Replacement Genuine Mazda rear exhaust silencer insulation panel for Mazda MX-5 Mk1 / NA models with applicable 1.6L and 1.8L petrol engines listed in the compatibility table.

The formed heat shield mounts beneath the rear floor above the exhaust back box.

It creates a thermal barrier between the hot exhaust silencer and the vehicle body, helping protect the rear floor, boot area, surrounding paint and nearby components from excessive radiant heat.

Age, road contamination and repeated heating and cooling can cause the original shield to corrode, crack, distort or detach around its mounting points.

A loose or damaged shield may also produce metallic rattling or vibration from beneath the rear of the vehicle.

This listing supplies one Genuine Mazda rear exhaust heat shield, which is the quantity required per applicable vehicle.

• Part type: Rear exhaust silencer heat shield
• Mazda catalogue description: Insulator
• Alternative descriptions: Rear floor heat shield / back-box heat shield / exhaust insulation panel
• Mazda diagram position: 56451
• Primary function: Protects the rear floor and chassis from exhaust-system heat
• System: Vehicle body and exhaust heat protection
• Fitting position: Beneath the rear floor above the exhaust back box
• Primary vehicle application: Mazda MX-5 Mk1 / NA
• Engine applications: Applicable 1.6L B6-family and 1.8L BP-family petrol engines
• Transmission applications: Manual and automatic according to vehicle specification
• Quantity required per vehicle: One
• Quantity supplied: One heat shield
• Brand: Genuine Mazda
• Part No.: NA01-56-451
• Also referenced as: NA0156451

Typical reasons for replacement:

• Original heat shield heavily corroded
• Mounting holes enlarged, cracked or torn
• Shield distorted or contacting the exhaust
• Metallic rattling from beneath the rear floor
• Shield detached or missing
• Rear floor or exhaust system being restored
• Exhaust back box being replaced
• Heat damage visible around the rear floor area

Fitment advice: This shield is fitted beneath the rear floor above the exhaust back box on applicable Mazda MX-5 Mk1 / NA models.

Position advice: This is the rear silencer heat shield. The MX-5 uses additional heat shields around other sections of the exhaust system, which have different shapes and part numbers.

Fastener advice: Inspect all mounting studs, nuts, bolts, washers and retaining clips. Corroded or missing hardware can allow the replacement shield to loosen and rattle.

Corrosion advice: Examine the surrounding rear floor and chassis metal carefully once the original shield has been removed. Repair significant corrosion before fitting the replacement panel.

Clearance advice: Confirm that the installed shield does not contact the exhaust back box, pipework, suspension or vehicle body. Adequate clearance is required to prevent noise and vibration.

Exhaust advice: Inspect the exhaust back box, hangers and mounting rubbers while access is available. A displaced or incorrectly supported exhaust may contact and damage the heat shield.

Heat-damage advice: Investigate any signs of discolouration, melted trim or excessive heat around the rear floor. A damaged exhaust, missing shield or incorrectly positioned silencer may be responsible.

Other items to consider: Consider inspecting or replacing the heat-shield fasteners, exhaust back box, exhaust mounting rubbers, clamps and adjacent floor protection according to their condition.

Useful tools / consumables: Suitable sockets and spanners, penetrating fluid, wire brush, rust-treatment products, torque wrench and safe vehicle-support equipment.

Difficulty guide: DIY Difficulty: Moderate. The vehicle must be raised and supported safely, and heavily corroded mounting hardware may require careful removal.

Why Genuine Mazda? Genuine Mazda heat shields are formed to the intended floor profile, mounting locations and exhaust-system clearances. Using the correct OE panel helps retain the original thermal protection without creating interference or vibration.

What’s in the box: One Genuine Mazda rear exhaust back-box heat shield, part number NA01-56-451. Mounting nuts, bolts, washers, clips, exhaust components and installation tools are not included unless specifically shown or stated separately.

Installation notes: Allow the exhaust system to cool fully and safely raise and support the vehicle. Apply penetrating fluid to corroded fasteners where required, remove the original shield and clean the surrounding mounting area. Inspect the rear floor and mounting points for corrosion or damage. Position the replacement shield correctly, fit suitable serviceable hardware and tighten it securely without deforming the panel. Confirm adequate clearance around the exhaust before lowering the vehicle.