Which parts fail
Components named in complaints (automatic and manual transmissions, CVT, axles, driveshaft, 4WD/AWD).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2001 Toyota 4Runner owners, lightly cleaned up (personal details are redacted by NHTSA).
Vehicle was parked in my gravel driveway. My home contractor smelled an odor & discovered that my rear was leaking gear oil. My husband, who is somewhat handy with cars, ended up sanding off lots of rust on the pumpkin, then cleaned it & used jb weld to seal where he thought the leak was coming from. (where the parking brake cable was attached.) this actually held for several years. Well, now at approx. 125,000 miles, the leak is back with a vengeance! And coming from a different place or places. The rust is bad. No one can believe it. I have taken it to the mechanic in town twice in the past 2 weeks, where he has tried to seal it while it was up on a lift, but it keeps leaking badly. I do not drive that often but do have to make a 100 mile round trip at least once a week, & upon arriving home just now, it is a mess again. My husband just put in about 20 oz. …
Tl* the contact owns a 2001 Toyota 4runner. While the contact was at an independent mechanic for a muffler replacement, he was informed that the vehicle frame was severely rusted. The mechanic stated that the muffler could not be replaced and a leak was present. The dealer (mcgee Toyota of hanover, 860 washington st, hanover, ma 02339, [phone]) informed the contact that the frame and differential housing needed to be replaced. The differential housing was repaired, but the frame was not. The manufacturer was made aware of the failures. The failure mileage was 170,000.
Tl* the contact owns a 2001 Toyota 4runner. The contact stated that while exiting out of a parking space, there was an oil stain on the ground. The contact noticed that the oil was leaking from the rear differential. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The approximate failure mileage was 98,528.
Since I got the car, the ignition key does not get in properly and sometimes does not start the car. The movement of the wheel helps sometimes. There have also been leaking engine covers that needed to be replaced. The structure gets rusty and there is problem with transmission.
Toyota 2001 4-runner, the vehicle has an excessive amount of underbody,frame,drive train rust specifically the rear differential housing unit. The problem first encountered was the rr. Differential housing rusted through and is leaking oil from it.so I called Toyota executive office and spoke with an executive analyst, I explained in detail what the problem was , she arranged for the vehicle to be taken to a Toyota dealer and inspected by their mechanics and the report reads as follows. Inspected rear differential , inspected housing -found fluid leaking from housing at yoke through rear cover ;metal porous and thin. Recommended replacement of housing and associated hardware repair estimate $1491.28 plus tax. They also noted several other issues that I cannot be sure if it was caused by excessive rust or normal wear. …
When driving at 70 MPH, the vehicle vibrates on the highway. I have taken the vehicle constantly to the dealership for over two years complaining about this problem and they always told me that nothing was wrong. Today (5/10/14), the mechanic at the dealership put the truck on a rack and ran the car at 45 MPH and there was visible vibration coming from the drive shaft and a loud noise that I could never hear from within the vehicle. All this time, I have been driving a vehicle that I was unaware could have snapped apart. The sound cannot be heard in the cabin, so I could not even report that as a problem until today. I purchased three sets of new tires, had shocks and struts replaced, and brake pads to no avail. Finally, after searching the web yesterday, I realized that this is a common problem with other vehicles of the same make and model. …
When on a long highway trip on the weekend of June 7, 2008, my husband noticed black spots on the rear window of our 2001 Toyota 4runner (121,000 miles). He cleaned it off to see if it returned as we resumed our journey. When we next stopped several hundred miles later, the black spots were on the entire rear of the vehicle. My husband checked beneath the rear of the vehicle and saw transmission fluid dripping out of the differential. We then took the vehicle to a mechanic who reported that the rear axle housing was completely corroded to the point of failure, and that it was beyond repair, and that he hadn't ever seen this on a car of this age and mileage. He informed us that Toyota has recently recalled tacoma vehicles from the same year for similar corrosion problems. We contacted Toyota and they said there was nothing they could do for us. …
The rear differential on my Toyota 4runner rusted so badly in 9 years of ownership that the structural steel frame that supports the differential gears (the housing) cracked and oil spilled out on the road. I discovered the rust during the yearly state inspection and consequently had the differential inspected by my Toyota dealer (berlin city portland, me) a few months back and they said it was structurally sound but rusty. I am an engineer and clearly it was not structurally sound or it would not have failed in short order as it did.... This failure could have caused the rear wheels to lock up resulting in a severe accident. This rust problem is common on most Toyota truck frames and drive trains owned in the north east. Toyota has elected to repair the trucks at no cost but not the 4runners with the same frame and differentials. This is dangerous as [redacted]... …
On the rear end differential housing, the back cover area (non replaceable) has become so porous because of heavy rust scaling and flaking that differential fluid seeps from it. The rest of the differential housing is made of thicker, heavier gauge metal and seems OK. This issue will cause the gear oil to drop below the required level causing differential failure or lock up and at highway speeds could be disastrous. When I realized I had this problem, I searched the Toyota forums online and it appears to be a very common issue with these vehicles and Toyota is aware but will do nothing about it. They will replace entire rusted out frames on trucks under recall, but refuse to address this issue? To add insult to injury they want $3000 to replace a known inferior/defective part. …
Driving down the highway in 2001 Toyota 4-runner going about 60 and all of a sudden the rear end/tires locked up and got it to the side of highway barely and then it started smoking really bad. Very lucky that it didn't cause a wreck or no one got hurt. Can't drive it or nothing, makes a loud knocking noise in the rear end and also when you turn the key on inside the vehicle all lights are on and its making a terrible buzzing noise. So had to have it towed and that cost me also and I need the whole rear differential and that's a lot of money. I've seen other problems/complaints about the same thing that happened to mine. I really think something should be done about it, Toyota should be fixing the problem and we shouldn't have to pay for it. Hopefully something gets done about this.
Transmission complaints in other 4Runner years
Frequently asked questions
How common are transmission problems on the 2001 Toyota 4Runner?
NHTSA has 32 complaints about the transmission & drivetrain of the 2001 Toyota 4Runner, 17% of the model year's 185 complaints. The component named most often is driveline (5 mentions).
Is there a recall for 2001 Toyota 4Runner transmission problems?
No. NHTSA lists no transmission & drivetrain recall for the 2001 Toyota 4Runner, though it has 1 recall for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2001 Toyota 4Runner transmission problems start?
Half of the complaints with a recorded mileage happened before about 122,000 miles, and 17% before 25,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.