2018 LEXUS IS 350

Typical onset: 60,000-120,000 mi

Symptoms: Rough idle and misfires that progressively worsen, Loss of power under acceleration, Check engine light with multiple misfire codes (P0300-P0306), Eventual catastrophic failure: scored cylinder walls, damaged pistons/rings

Fix: Direct injection creates valve carbon over time; severe cases see carbon chunks break off and score cylinders. Early stages: walnut blasting ($500-800, 4-6 hrs). Advanced damage requires short block replacement or full rebuild: 18-25 labor hours plus machine work. Some owners report Lexus goodwill assistance even out of warranty due to design flaw recognition.

Estimated cost: $8,000-15,000

Typical onset: 70,000-110,000 mi

Symptoms: Transmission fluid spots under vehicle near front, Burnt transmission fluid smell, Low fluid level on dipstick, Occasional harsh shifts if fluid gets critically low

Fix: The cooler lines where they connect to the radiator corrode and seep, eventually rupturing. Replacement involves cooler lines and often the external cooler assembly itself. 2-3 labor hours, must refill and flush ATF.

Estimated cost: $600-1,200

Typical onset: 80,000-130,000 mi

Symptoms: Clunk when shifting from Park to Drive/Reverse, Vibration at idle in gear, Excessive driveline movement visible when revving in gear with brakes applied

Fix: The rear mount degrades from heat and age; rubber separates from metal bracket. Straightforward replacement, accessible from underneath. 1.5-2 labor hours.

Estimated cost: $300-500

Symptoms: No-start condition or engine stalling while driving, Rough running and hesitation under load, Check engine light with fuel trim/pressure codes

Fix: NHTSA recall for low-pressure fuel pump impeller cracking (density issue from supplier). Dealership replaces pump assembly under recall at no cost. If not recalled or post-recall failure: 2-3 labor hours to drop tank and replace pump module.

Estimated cost: $0 (recall) or $800-1,400

Typical onset: 90,000-140,000 mi

Symptoms: Coolant seepage or dried residue on pump housing, Slight coolant smell after engine heat-soak, Gradual coolant level drop over weeks

Fix: 2GR pump seals age out; often seep before catastrophic failure. Preventive replacement recommended if seepage detected. Timing belt-driven access, so many do pump + thermostat together. 4-5 labor hours.

Estimated cost: $900-1,500

Typical onset: 40,000+ mi

Symptoms: Rattle from upper dash area over bumps, Creaking from A-pillar trim or door panels, Increased cabin noise with age

Fix: Lexus interiors generally age well, but clip fatigue and panel fit tolerance lead to squeaks. Diagnosis takes patience; fixes involve felt tape, clip replacement, and trim re-securing. 1-3 labor hours depending on source. Purely annoyance—no functional impact.

Estimated cost: $150-400