2003 MAZDA RX-8

Typical onset: 60,000-100,000 mi

Symptoms: Hard cold starts requiring extended cranking, especially below 40°F, Loss of power above 6,000 RPM, Excessive fuel consumption beyond the already poor 16-18 MPG, Failed compression test showing under 6.5 kg/cm² on any rotor face

Fix: Complete engine rebuild or replacement. Apex seals wear from carbon buildup, heat cycling, and oil starvation. DIY rebuild takes 25-35 hours with specialty tools; most owners opt for reman long-block swap at 12-16 hours labor. Preventable with religious oil checks (every fill-up), premium fuel, and occasional Italian tune-ups to redline.

Estimated cost: $4,500-7,500

Typical onset: 40,000-80,000 mi

Symptoms: Misfires under load, CEL with P0300-P0304 codes, Rough idle that smooths above 3,000 RPM, Fouled spark plugs found during inspection

Fix: RX-8 runs four coils (two leading, two trailing) and they fail frequently due to heat. Replace all four plus plugs as a set; doing one at a time guarantees a comeback. 1.5-2.5 hours labor. OEM or quality aftermarket only—cheap coils fail in under 10k miles.

Estimated cost: $600-900

Symptoms: Engine cranks endlessly but won't fire after being shut off cold, Strong fuel smell from exhaust during cranking, Spark plugs wet with gasoline when removed

Fix: Rotary engines flood easily if shut off before reaching operating temp. De-flood procedure: pull fuel pump fuse, hold throttle wide open, crank 8-10 seconds. If that fails, pull all four plugs, dry/clean them, reinstall, repeat procedure. 0.5-1.5 hours if you've done it before. Prevention: never shut off a cold engine—let it warm to 160°F minimum, or rev to 3,000 RPM for 10 seconds before shutdown.

Estimated cost: $80-200

Typical onset: 50,000-90,000 mi

Symptoms: CEL with P0420 catalyst efficiency code, Loss of power, especially mid-range throttle response, Rattling from exhaust on startup (substrate breakup), Failed emissions test

Fix: Rotary oil consumption kills cats prematurely. Main cat is integrated into the exhaust manifold (expensive). Aftermarket high-flow options exist but may not pass strict emissions states. 2-3 hours labor for cat replacement. Check local laws before going aftermarket.

Estimated cost: $800-1,800

Typical onset: 60,000-100,000 mi

Symptoms: Clunk when shifting from reverse to drive, Excessive drivetrain movement visible from engine bay during throttle blips, Vibration at idle that wasn't there before

Fix: Rear trans mount (PPF mount) and front engine mounts wear from the rotary's inherent vibration. Trans mount alone is 1.5-2 hours; all mounts together 3-4 hours. Use OEM or quality polyurethane upgrades—cheap rubber mounts last 18 months.

Estimated cost: $400-700

Typical onset: 80,000-120,000 mi

Symptoms: No start, no fuel pressure at rail (should be 60 PSI), Intermittent stalling at highway speeds, Whining noise from rear seat area under acceleration

Fix: In-tank pump fails, often without warning. Tank drop required on the RX-8. 2.5-3.5 hours labor. Use OEM Mazda pump—aftermarket units frequently cause lean conditions that accelerate apex seal wear.

Estimated cost: $600-900

Typical onset: 70,000-110,000 mi

Symptoms: Click-click-click but no crank (not a dead battery), Intermittent no-start requiring multiple key cycles, Grinding noise during start attempt

Fix: High compression rotary engines are brutal on starters. Replacement is straightforward but tight workspace. 1.5-2 hours labor. Always check battery and cables first—weak battery mimics starter failure and kills new starters prematurely.

Estimated cost: $400-650