2012 LEXUS IS 350

Typical onset: 60,000-100,000 mi

Symptoms: Rough idle, hesitation on cold starts, Reduced power, occasional misfire codes (P030X), Poor fuel economy, Car runs better after sustained highway driving

Fix: Walnut-blasting the intake valves is the proper fix, requires intake manifold removal and 4-6 hours of labor. Some shops use chemical cleaning (less effective). Catch cans can slow recurrence but won't reverse existing buildup.

Estimated cost: $600-1,200

Typical onset: 80,000-150,000 mi

Symptoms: Excessive oil consumption (1 quart per 1,000-2,000 mi), Blue smoke on startup or under load, Rattling from cylinder head area, metallic ticking, Check engine light with low compression on one or more cylinders

Fix: Lexus Warranty Enhancement Program ZE4 covers up to 10 years / unlimited miles from original in-service date for piston replacement (pistons 2 and 4 crack most often). Outside warranty, you're looking at a shortblock or full engine rebuild with 18-25 hours labor. Many owners had this covered under ZE4 even past 100k miles.

Estimated cost: $0 if ZE4 eligible, $6,000-10,000 out-of-warranty

Typical onset: 90,000-140,000 mi

Symptoms: Transmission fluid puddle under car, usually left-front area, Low transmission fluid warning (if equipped), Pink or red fluid drips, distinct sweet smell, Harsh shifting or slipping if fluid level drops significantly

Fix: Rubber hoses from transmission to cooler (runs through radiator) deteriorate and split. Replace both feed and return lines as a pair, plus top off ATF. 2-3 hours labor. Don't ignore—running low on ATF will cook the transmission.

Estimated cost: $400-700

Symptoms: Recall notice by mail, No symptoms until inflator ruptures in a crash, spraying metal shrapnel

Fix: Multiple Takata airbag recalls affecting passenger-side inflator. Lexus dealers replace at no cost. Check VIN at NHTSA.gov—critical safety issue, do not skip. Takes 1-2 hours at dealer, parts often backordered so schedule early.

Estimated cost: $0 (recall)

Symptoms: Dashboard becomes sticky or glossy, especially in hot climates, Melted or deformed appearance on upper dash surface, Sticky residue transfers to hands or rags

Fix: Lexus issued Customer Support Program (CSP) for melting dashboards through 2016, but most 2012 IS models aged out of eligibility. Aftermarket dash covers or professional re-skin are the only practical fixes. Cosmetic only, but annoying and tanks resale value.

Estimated cost: $50-200 for cover, $1,500-2,500 for professional re-skin

Typical onset: 80,000-120,000 mi

Symptoms: Clunking over bumps, especially at low speeds, Steering feels loose or vague on center, Inner-edge tire wear, Alignment won't hold after fresh adjustment

Fix: Rubber bushings in front lower control arms crack and separate. Some shops press new bushings (1.5 hours per side), but most replace whole arms (easier, 2-3 hours for both sides). Do an alignment after. Common wear item on RWD sport sedans.

Estimated cost: $500-900 for both sides with alignment