Intermittent CEL flicker plus a rough idle on a Mazda MX-5 IV usually points to a misfire or unstable fuel/air mixture. Start with codes, then check plugs, coils, injectors, and intake leaks.
What a flickering check engine light means on an MX-5 IV
On a Mazda MX-5 IV (ND), a check engine light that flickers or flashes while the idle is rough is usually the car telling you about a misfire — often a random or intermittent one. The light may not stay on steadily because the misfire comes and goes, especially at idle. That does not automatically mean the engine is about to fail, but a flashing CEL is a stronger warning than a steady one because unburned fuel can overheat the catalytic converter. The first step is not guessing parts: scan all stored and pending codes, check freeze-frame data, and look at misfire counters live if you have a scan tool that can do it. Codes like P0300, P0301–P0304, P0171, P0172, or P0101 give you a direction before you open the hood.
