2021 HONDA S660

Typical onset: 40,000-70,000 mi

Symptoms: Shuddering or hesitation during acceleration, especially when warm, Transmission temperature warning light on spirited drives or hot days, Delayed engagement when shifting from Park to Drive

Fix: CVT fluid degrades quickly under track or canyon use. Full fluid exchange with Honda CVT-F fluid (3-4 quarts) often restores smooth operation. If judder persists, transmission oil cooler may need flushing or replacement (2.5 hrs). Severe cases require CVT replacement or valve body work (8-12 hrs), but fluid service catches most issues early.

Estimated cost: $250-600 for fluid service; $3,500-5,500 for cooler and valve body work

Typical onset: 60,000-90,000 mi

Symptoms: Rattling noise from engine on cold start that fades after 5-10 seconds, Metallic ticking under acceleration, Check engine light with VTC (Variable Timing Control) codes

Fix: The S07A's high-revving nature stresses the timing chain system. Tensioner and guides wear faster than larger Honda engines. Requires timing chain, tensioner, guides, and VTC actuator replacement. Engine must be partially dropped for access (10-14 hrs labor). Skipping this leads to jumped timing and bent valves.

Estimated cost: $2,200-3,800

Typical onset: 50,000-100,000 mi

Symptoms: Persistent ticking from valve cover, louder when cold, Noise increases with RPM but doesn't affect performance initially, May develop into misfires if ignored past 100k miles

Fix: The S07A uses solid lifters that require periodic valve adjustment (every 30k miles per Honda JDM service schedule, often skipped by importers). Noise alone doesn't require lifter replacement—just adjustment (2.5 hrs). If clearances are excessive or lifters scored, all 6 lifters should be replaced along with camshaft inspection (6-8 hrs including head removal).

Estimated cost: $300-450 for adjustment; $1,800-2,800 for lifter replacement

Typical onset: 70,000-110,000 mi

Symptoms: Rattling sound from engine bay at idle, disappears under boost, Slight loss of low-end torque, Occasional overboost or underboost codes

Fix: Wastegate actuator rod and flapper develop play over time. Turbo rebuild or replacement is the proper fix (5-7 hrs labor due to mid-engine layout and limited access). Aftermarket actuators available but require tuning. This is a wear item on small turbos running high boost from the factory.

Estimated cost: $1,200-2,400

Typical onset: 50,000-80,000 mi

Symptoms: Excessive vibration through chassis at idle, Clunking when shifting into gear or accelerating from stop, Visible sagging of CVT when inspected from below

Fix: The rear transmission mount (connecting CVT to subframe) uses soft rubber that degrades quickly, especially with aggressive driving. Replacement is straightforward but requires supporting the transmission (1.5-2 hrs). Upgraded polyurethane mounts available but transmit more NVH.

Estimated cost: $250-450

Symptoms: Stumbling or hesitation under hard acceleration, Difficulty starting after sitting overnight, Intermittent loss of power at highway speeds

Fix: Many imported S660s sat in Japan or at port for extended periods, allowing fuel to degrade and varnish to form in the filter. The in-tank filter isn't regularly serviced per Honda schedule but should be replaced on any import (2-3 hrs to drop tank). Use OEM Honda filter only—aftermarket often doesn't fit kei car fuel pumps correctly.

Estimated cost: $300-550