← Mazda Miata NB (1999-2005 US model years) problems
NB1 ignition coil packs wear out and can damage the cat
Reported · Severity: Medium · Years: 1999-2000 (NB1)
Symptoms
Misfires, hesitation, stalling, idle problems.
Cause
A forum problem list and a year-by-year page both say the NB1 coil packs fail; the latter says failing coils can damage the catalytic converter. A forum poster notes NB2 uses a different ignition system without this issue.
Fix (summary)
Replace coils and wires with plugs as a set; same forum thread suggests a cooler NGK heat range for the stock copper plugs.
Related parts
Sources
- Common Issues with NB 1998-2005 Miatas — MX-5 Miata Forum (forum thread; read 2026-10-15; search excerpt only)
- Miata problems/maintenance by year — miatayear.com (editorial; read 2026-10-15; search excerpt only)
Summaries are in our own words. Not repair instructions; consult the factory service manual.