IsItAGoodCar
Reliability Guide

Common Problems with the
2005 Mazda RX-8

We've identified 3 known issues that can affect the 2005 Mazda RX-8. 2 of these are serious faults that could be expensive to repair.

3
Known Issues
2
Serious
1
Moderate
0
Minor

All Known Issues

Low Compression and Hot-Start Failure

SeriousEngine

Wear in the rotary engine reduces compression, making the car increasingly hard to restart when warm and often leading to an expensive rebuild.

Est. Repair Cost: £2,500–£5,000
Warning Signs:

Long cranking when hot, Weak idle, Loss of power high in the rev range

What to Inspect:
  • Insist on a rotary compression test
  • Start it fully cold and restart it hot
  • Be wary of sellers who only talk about mileage
Verified by IsItAGoodCar Research Team

Rear Arch and Sill Corrosion

SeriousBodywork & Rust

UK RX-8s rot around the rear arches, sills and front chassis rails, and fresh underseal can hide serious structural work.

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

Bubbling paint around arches, Rusty inner sills, Corrosion advisories on MOT history

What to Inspect:
  • Inspect the rear arch lips and sill ends
  • Check under the front floor and chassis rails
  • Avoid cars with suspiciously fresh underseal and no photos
Verified by IsItAGoodCar Research Team

Ignition Coil Failure and Catalytic Converter Damage

ModerateEngine

Weak coils cause misfires and incomplete combustion, which can quickly overheat and destroy the catalyst on a rotary that already burns oil by design.

Est. Repair Cost: £250–£1,200
Warning Signs:

Misfire under load, Strong fuel smell, Engine warning light or failed emissions test

What to Inspect:
  • Ask when the coils, plugs and leads were last changed
  • Listen for a crisp idle
  • Check for catalyst or emissions-related invoices
Verified by IsItAGoodCar Research Team

Buying Tips for 2005 Mazda RX-8

  • ✓A proper hot-and-cold compression test is far more important than a shiny body or low odometer reading.
  • ✓Check for evidence of regular ignition-coil, plug and lead replacement; weak ignition quickly damages the catalytic converter.
  • ✓Inspect rear arches, sills and front chassis rails carefully because rusty shells can make even a good engine uneconomic.
  • ✓Check the oil level before and after every test drive—the rotary engine consumes oil by design, and low levels cause rapid wear.
  • ✓Listen for a smooth idle and strong pull to the redline; a lazy or smoky engine likely needs a rebuild.
  • ✓Verify that the catalytic converter is original or a quality replacement—cheap cats clog quickly on a rotary.
Check a 2005 Mazda RX-8 by Registration