The 2021 4Runner with the 4.0L V6 (1GR-FE) is a generally solid truck, but the frequent transmission oil cooler failures and well-documented secondary air injection issues can bite owners hard. Engine rebuild frequency in the data suggests either premature wear from deferred maintenance or aftermarket abuse.
Symptoms: Milky or pink transmission fluid (coolant mixing), Transmission slipping, delayed shifts, or limp mode, Overheating transmission temp gauge reading
Fix: Replace external cooler and flush system if caught early (2-3 hrs). If coolant entered transmission, full rebuild or replacement required (12-18 hrs labor). This is a known Toyota weak point across multiple platforms.
Estimated cost: $800-6,500
Secondary Air Injection System Failure (P0410, P0418, P0419)
Common · low severity
Typical onset: 70,000-110,000 mi
Symptoms: Check engine light with P0410/P0418/P0419 codes, Rattling or buzzing noise on cold start for 60-90 seconds, No drivability issues, emissions test failure in strict states
Fix: Air pump or one-way valves fail. Pump replacement 2 hrs, valve replacement 1.5 hrs. Many owners delete the system entirely if emissions testing allows (1 hr plus tune).
Estimated cost: $600-1,400
Front Lower Ball Joint Wear
Occasional · medium severity
Typical onset: 80,000-130,000 mi
Symptoms: Clunking over bumps at low speed, Wandering steering or loose feel, Uneven tire wear on inside edge
Fix: Ball joints are pressed into lower control arms. Replace both sides (alignment required). 3-4 hrs labor. Aftermarket heavy-duty options available for off-road use.
Estimated cost: $700-1,200
Exhaust Manifold Leak / Cracking (Driver Side)
Occasional · low severity
Typical onset: 90,000-150,000 mi
Symptoms: Ticking or tapping noise from engine bay on cold start, Smell of exhaust in cabin with heat on, Visible soot around manifold gasket area
Fix: Driver-side manifold cracks or gasket fails. Manifold replacement is 5-6 hrs due to tight clearances. Gasket-only job if caught early is 3 hrs.
Estimated cost: $800-1,800
Premature Piston Ring Wear / Oil Consumption (Abused or Neglected Units)
Rare · high severity
Typical onset: 100,000-180,000 mi
Symptoms: Burning more than 1 quart per 1,000 miles, Blue smoke on deceleration or startup, Low compression on cylinder leak-down test
Fix: The 1GR-FE is typically bulletproof, but extended oil changes or aggressive off-road use without proper cooling can cause premature ring wear. Engine rebuild or short-block replacement: 18-24 hrs labor.
Estimated cost: $4,500-8,000
Radiator Plastic Tank Cracking
Occasional · medium severity
Typical onset: 100,000-140,000 mi
Symptoms: Coolant leak from radiator end tank, Overheating under load or in traffic, Visible coolant pooling under vehicle
Fix: Plastic end tanks crack with age and heat cycles. Radiator replacement is straightforward: 2 hrs labor. Use OEM or quality all-aluminum aftermarket.
Symptoms: Hard starting after sitting, Sputtering or stumbling under acceleration, Check engine light with fuel trim codes
Fix: In-tank pump and filter are combined. Failure is rare unless bad fuel introduced. Drop tank, replace pump assembly: 3 hrs labor.
Estimated cost: $600-1,100
Owner tips
Change transmission fluid every 50k-60k miles even though Toyota says 'lifetime'—cooler failures contaminate fluid and kill transmissions.
Inspect front lower ball joints at every alignment; replace before they fail to avoid control arm damage.
If secondary air codes appear, verify pump operation before replacing valves—both fail independently.
Use 0W-20 synthetic and stick to 5k-7k oil changes if you off-road or tow; the 1GR-FE hates extended intervals under load.
Check radiator end tanks for hairline cracks during coolant service at 100k—catch it before it strands you.
Buy it used—the 4Runner is dead-reliable if maintained, just budget $1,500 for the inevitable trans cooler and secondary air repairs around 80k miles.
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 engine bay location; top post terminal configuration
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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 2021 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.