The 2007 Highlander is generally solid but the 3.3L V6 has a critical engine sludge vulnerability, and all non-hybrid models share a transmission oil cooler failure that can destroy the transmission if ignored.
3.3L V6 Engine Sludge and Catastrophic Failure
Occasional · high severityTypical onset: 80,000-150,000 mi
Symptoms: excessive oil consumption (1+ quart per 1,000 mi), check engine light with misfire codes, knocking or ticking from engine, sudden loss of power, blue smoke from exhaust
Fix: The 3.3L 3MZ-FE is prone to sludge buildup that starves oil to pistons and rings, causing consumption and eventually spun bearings or seized engines. If caught early with consumption only, you're looking at piston ring replacement (16-20 hours). If bearings are gone, it's either a short block (22-28 hours) or used engine swap (18-24 hours). Many owners don't catch it until catastrophic failure.
Estimated cost: $4,500-8,500
Transmission Oil Cooler Line Failure (Pink Milkshake)
Common · high severityTypical onset: 90,000-140,000 mi
Symptoms: transmission slipping or delayed engagement, pink or strawberry milkshake appearance in radiator coolant, transmission overheating, radiator coolant in transmission pan
Fix: The internal transmission cooler in the radiator develops cracks, allowing coolant and ATF to mix. This contaminates the transmission and destroys clutch packs and valve body within days if driven. Proper fix requires radiator replacement, complete transmission fluid system flush with new cooler lines, filter, and pan drop (6-8 hours). If transmission is damaged, add rebuild or replacement (12-16 hours for R&R plus rebuild cost).
Estimated cost: $1,200-2,000 (if caught early), $3,500-5,500 (with transmission damage)
Transmission Mount Failure
Common · medium severityTypical onset: 70,000-120,000 mi
Symptoms: clunk when shifting from park to drive or reverse, excessive vibration at idle, visible engine movement when revving in park, transmission thump during acceleration
Fix: The rear transmission mount (engine side) deteriorates and separates, allowing excessive drivetrain movement. Replacement is straightforward but requires supporting the transmission from below. 2-3 hours labor. Often done with front engine mounts at same time if those are soft.
Estimated cost: $350-600
Power Steering Rack Leak
Occasional · medium severityTypical onset: 100,000-160,000 mi
Symptoms: power steering fluid dripping from bellows boots, low fluid warnings, whining noise when turning, stiff steering when cold
Fix: Rack seals fail and leak fluid into the bellows, eventually dripping onto subframe. Toyota racks are not rebuildable in field, so it's rack replacement (4-5 hours), which requires alignment afterward. Fluid pump can also fail but rack leaks are more common.
Estimated cost: $900-1,400
Front Lower Control Arm Bushings
Common · low severityTypical onset: 80,000-130,000 mi
Symptoms: clunking over bumps, wandering or vague steering feel, uneven tire wear on inside edges, steering wheel off-center after hitting potholes
Fix: The large front lower control arm bushings wear out and cause alignment issues and handling slop. Arms come as assemblies (bushings not sold separately by Toyota), so it's full arm replacement on both sides. 3-4 hours plus alignment. Aftermarket bushings exist but require press work.
Estimated cost: $700-1,100
Evaporative Emissions Charcoal Canister Failure
Occasional · low severityTypical onset: null
Symptoms: check engine light with P0441 or P0446 codes, difficulty filling gas tank (pump clicks off repeatedly), fuel smell near rear of vehicle, failed emissions test
Fix: The evap canister can crack or clog, especially if vehicle was topped off repeatedly at gas station (liquid fuel damages charcoal). Canister is mounted behind rear bumper near spare tire. Replacement is 1.5-2 hours but diagnosis can be tricky (smoke test recommended). Vent valve on top of canister also fails occasionally.
Estimated cost: $400-700
Avoid the 3.3L V6 unless full service records prove religious oil changes; the 2.4L I4 and hybrid 3.0L are far more reliable, and all need the transmission cooler lines watched closely.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.