IsItAGoodCar
Reliability Guide

Common Problems with the
2002–2004 Mazda MX-5 (NB)

We've identified 3 known issues that can affect the 2002–2004 Mazda MX-5 (NB). 2 of these are serious faults that could be expensive to repair.

3
Known Issues
2
Serious
1
Moderate
0
Minor

All Known Issues

Front Chassis Rail Corrosion

SeriousBodywork & Rust

NB cars can rust badly inside the front chassis rails, sometimes while the outer structure still looks respectable from above.

Est. Repair Cost: £800–£2,500
Warning Signs:

Crunchy metal around front rail seams, MOT advisories near front structure, Fresh underseal on repaired rails

What to Inspect:
  • Inspect the front rails from underneath
  • Look for swelling or distortion around the rail seams
  • Do not rely on photos taken from above the engine bay
Verified by IsItAGoodCar Research Team

Rear Sill and Arch Rust

SeriousBodywork & Rust

Like the NA, the NB traps moisture around the rear sill sections and arch returns, so rot often starts where it is easy to hide with cosmetic repairs.

Est. Repair Cost: £500–£1,800
Warning Signs:

Bubbling paint ahead of rear wheels, Uneven rear arch repairs, Rusty inner lip around the sill closing panel

What to Inspect:
  • Inspect both rear sill sections closely
  • Check for filler or mismatched paint
  • Read the MOT history for repeated corrosion notes
Verified by IsItAGoodCar Research Team

Blocked Hood Drains and Cabin Damp

ModerateBodywork & Rust

When the soft-top drains block, water can back up into the cabin and accelerate rust in the sills and floor area.

Est. Repair Cost: £0–£250
Warning Signs:

Wet carpets, Condensation inside the car, Musty smell after rain

What to Inspect:
  • Feel both footwells and the carpet behind the seats
  • Ask if the drains are cleaned routinely
  • Check for corrosion starting around drain exits
Verified by IsItAGoodCar Research Team

Buying Tips for 2002–2004 Mazda MX-5 (NB)

  • ✓Inspect the front chassis rails as carefully as the rear sills; this is the hidden structural failure point on many NB cars.
  • ✓Check the hood drains and footwells for damp, especially on cars that live outside.
  • ✓Rust-free cars with strong evidence of preventative undersealing are worth a premium.
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Check a 2002–2004 Mazda MX-5 (NB) by Registration