The 2020 4Runner with the 4.0L V6 (1GR-FE) is generally robust, but this engine generation has known piston-slap issues and potential head gasket failures at higher mileage. The transmission oil cooler is a weak point that can cause catastrophic trans failure if it leaks internally.
Piston Slap / Cold-Start Knock (1GR-FE Engine)
Common · medium severity
Typical onset: can start as early as 30,000-60,000 mi, worsens over time
Symptoms: Pronounced knocking or rattling on cold starts for first 30-60 seconds, Noise diminishes as engine warms up, May progress to oil consumption (burning oil) as wear increases, Check engine light with misfire codes in severe cases
Fix: If just noise and minimal oil consumption, many run it as-is for years. If burning >1 qt per 1,000 mi or metal found in oil, requires short block replacement or full rebuild with oversized pistons. 18-24 labor hours for short block swap.
Estimated cost: $4,500-7,500
Head Gasket Failure (External Leak)
Occasional · high severity
Typical onset: 80,000-150,000 mi
Symptoms: Coolant weeping from between head and block, usually driver side, Sweet smell after drive, coolant puddles under vehicle, Overheating if coolant level drops significantly, White smoke from exhaust if internal leak develops (rare on 1GR)
Fix: Both heads should be done at once even if only one side leaks. Requires heads off, resurfacing recommended, timing components while you're in there. 12-16 labor hours.
Estimated cost: $2,800-4,200
Transmission Oil Cooler Failure (Internal Leak)
Occasional · high severity
Typical onset: 60,000-120,000 mi
Symptoms: Transmission fluid appears milky or strawberry-milkshake pink (coolant mixing), Erratic shifting, slipping, or loss of gears, Transmission overheating warnings, Coolant loss with no visible external leak
Fix: Cooler is integrated into the radiator. Requires new radiator, complete trans fluid flush (possibly multiple times), and often transmission rebuild if contamination went unnoticed. Caught early: 4-6 hours for radiator and flush. With trans damage: add 18-24 hours for rebuild.
Estimated cost: $800-1,200 (radiator/flush only); $4,000-6,500 (if trans rebuild needed)
Secondary Air Injection (AIR) Pump Failure
Occasional · low severity
Typical onset: 70,000-100,000 mi
Symptoms: Check engine light with P0410, P0418, P0419 codes, Loud whirring or grinding noise on cold starts (first 90 seconds), Emissions test failure in states that check, No drivability impact, engine runs fine
Fix: AIR pump and/or one-way valves fail. Pump alone is 2-3 labor hours. Some owners delete the system in non-emissions states, but technically not legal.
Estimated cost: $600-1,200
Exhaust Manifold Studs / Leaks
Occasional · low severity
Typical onset: 80,000-130,000 mi
Symptoms: Ticking or tapping noise from engine bay, especially on cold starts, Smell of exhaust fumes in cabin or engine bay, Visible soot marks at manifold-to-head junction, May set check engine light if leak is severe enough to affect O2 sensors
Fix: Exhaust manifold studs corrode and break. Requires manifold removal, drilling out broken studs, installing new studs and gaskets. 4-6 labor hours per side if studs snap off flush.
Estimated cost: $800-1,500 per side
Lower Ball Joints (Premature Wear)
Common · medium severity
Typical onset: 60,000-100,000 mi, sooner with lift kits or aggressive off-roading
Symptoms: Clunking noise over bumps, especially from front end, Steering wander or vague on-center feel, Uneven or excessive tire wear on inside edge, Play detectable when prying on tire with vehicle on jack stands
Fix: OEM ball joints are not serviceable separately; requires entire lower control arm replacement per side. 2-3 hours per side with alignment afterward.
Estimated cost: $600-1,000 per side (parts + labor + alignment)
Rear Differential Pinion Seal Leak
Occasional · low severity
Typical onset: 50,000-90,000 mi
Symptoms: Gear oil dripping from front of rear diff where driveshaft enters, Oil spots on driveway, centered under rear axle, Whining noise from rear end if fluid level drops significantly, No drivability issues if caught early and topped off
Fix: Pinion seal replacement. Requires driveshaft removal, pinion nut torque spec is critical (crush sleeve). 2-3 labor hours.
Estimated cost: $400-700
Owner tips
Change transmission fluid every 60k mi despite 'lifetime' claim—cooler failures are brutal on the A750F trans
Monitor oil consumption closely if you hear piston slap; some engines burn oil from factory, others develop it later
Use quality coolant and change every 100k mi—cheap coolant accelerates head gasket deterioration on this engine
If you lift or run larger tires, budget for ball joints and alignment every 50-60k mi
Check for TSBs on squeaks and rattles; Toyota issued several for interior trim and dash noise fixes under warranty
Solid truck if you accept piston slap noise and watch the trans cooler like a hawk—better bet than a same-year domestic SUV, but not bulletproof like the legend suggests.
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.
Fitment notes: Standard top post battery; located in engine bay
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Every control module on the 2010-2024 Toyota 4Runner — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
⚠️ Optional equipment. Sensor calibration required after replacement.
Engine Control Module / Powertrain Control Module (ECM/PCM)1.2 hr R&Rdealer / factory tool +1.0 hr▸ programming details
📍 Under passenger seat or behind glove box
🔧 Toyota Techstream
⚠️ VIN registration, immobilizer pairing, and calibration required. TIS subscription mandatory for programming.
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
Southeast Toyota Distributors, LLC (SET) is recalling certain 2020-2022 4Runner vehicles equipped with 20-inch Black Gunner Wheels. The load carrying capacity modification labels are incorrect. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 110, "Tire Selection and Rims."
Consequence: An incorrect label may lead to unintentionally overloading the vehicle, increasing the risk of a crash.
Remedy: SET will mail replacement labels to owners, free of charge. Owner notification letters are expected to be mailed September 4, 2022. Owners may contact SET's customer service at 954-429-2000. SET's number for this recall is SET22A.
Performance
Horsepower
270hp
Torque
278lb-ft
0–60 mph
7.5sec
Quarter mile
15.7sec
Top speed
112mph
Fuel economy (EPA)
City
16mpg
Highway
19mpg
Combined
17mpg
Fuel
Regular Gasoline
Capability & size
Towing capacity
5,000lb
Payload
1,440lb
Curb weight
4,805lb
EPA class
Standard Sport Utility Vehicle 4WD
Wiper blades
5th generation 4Runner; standard hook attachment for front blades
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2020 Toyota 4Runner 4.0L V6 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.