2021 TOYOTA HIGHLANDER

Typical onset: 40,000-80,000 mi

Symptoms: Low oil warning light appearing between oil changes, Burning oil smell from exhaust, Blue smoke on cold start or acceleration, Sudden knocking or loss of power if oil starvation occurs, Check engine light with misfire codes

Fix: D-4S direct injection piston ring design allows carbon buildup and ring flutter, leading to 1 qt per 1,000 miles consumption or worse. Minor cases may respond to top-end cleaning and ring soak treatments (4-6 hours labor). Severe cases require full engine rebuild with updated pistons and rings (25-35 hours), or short block replacement (20-28 hours). Toyota has extended warranty coverage on some VINs but not all qualify.

Estimated cost: $6,500-12,000

Typical onset: 50,000-90,000 mi

Symptoms: Red fluid pooling under vehicle near front, Transmission temperature warning on dashboard, Burnt transmission fluid smell, Slipping or delayed engagement when hot

Fix: Cooler line fittings corrode or crack where they connect to radiator assembly, particularly in salt-belt states. Requires cooler line replacement and sometimes radiator if integrated cooler is damaged. 2-3 hours labor plus fluid flush. Catch it early before transmission overheats.

Estimated cost: $450-850

Typical onset: 60,000-100,000 mi

Symptoms: Clunking when shifting from park to drive or reverse, Vibration through cabin at idle, especially with A/C on, Excessive engine rocking visible from outside during acceleration, Transmission shifter feels sloppy

Fix: Rear transmission mount separates or hydraulic portion fails, allowing powertrain to shift excessively. Requires subframe lowering on some trims for access. 2.5-4 hours labor depending on AWD configuration. Often replace engine mounts at same time if original.

Estimated cost: $550-950

Typical onset: 70,000-110,000 mi

Symptoms: White sweet-smelling exhaust smoke, Coolant loss with no visible external leaks, Overheating under load, Milky oil on dipstick or oil cap, Coolant in overflow tank bubbling at idle

Fix: Some early 2020-2021 model year V6 engines had head gasket sealing issues, possibly related to block deck machining tolerances. Both heads typically need to be done. 18-24 hours labor includes machining if heads are warped. Must pressure test block for cracks before reassembly.

Estimated cost: $4,200-6,800

Typical onset: null

Symptoms: Rough idle or stalling after refueling, Loss of power under acceleration, Check engine light with fuel trim codes, Hard starting after sitting overnight, Hesitation at highway speeds

Fix: In-tank fuel pump assembly filter screens clog prematurely, possibly from contaminated fuel or tank debris. Some correlation with specific fuel brands or stations. Requires dropping tank and replacing entire pump assembly (filter not serviceable separately on this generation). 3-4 hours labor.

Estimated cost: $850-1,400