Acid rain results from rainwater or other airborne moisture that become acidic due to industrial chemical impurities in the atmosphere. If these acidic compounds settle on an exposed vehicle, especially the horizontal areas such as the hood, roof, and decklid, significant damage to the painted surfaces can occur. Acid rain damage can typically be identified on vehicles by the presence of stains on the paint surface that resemble hard water spots. Unlike water spots however, acid rain damage cannot be removed by regular washing procedures. Also, because acid rain can etch and soften the paint, normal buffing or polishing repair procedures should not be attempted. This can cause further damage
full bulletin at NHTSA ↗2006 Toyota 4Runner body problems
moderate 115 complaints filed with NHTSA · avg repair $1,500 · see body across all vehicles →
Failure mileage
Complaints
115
Recalls
0
Avg fix
$1,500
2crashes
When does it fail?
Of the 115 body complaints filed for the 2006 Toyota 4Runner, here's the actual mileage breakdown — failures cluster heaviest at 75,000-100,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
Body accounts for 30% of every owner complaint on file for this vehicle — the dominant problem area across 11 categories tracked.
Owners have filed 115 body complaints with NHTSA against this vehicle, but no formal recall covers the issue — the federal record reflects what manufacturers have admitted, not everything owners are reporting.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering body on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
To prevent brake rotor rust from forming during transportation and storage, wheel film will be used instead of a cardboard type of anti-rust cover. The purpose of the wheel film is to shield the disc brake rotor from weather elements and initial rust before the vehicle is delivered to the customer. Consequently, the film should remain on the wheel for as long as possible.
full bulletin at NHTSA ↗The condition known as acid rain is caused by airborne chemicals or particles in the atmosphere, which mix with rainwater, nighttime dew, or high humidity to form acidic compounds. If these contaminants settle and remain on a painted vehicle surface, especially the horizonal areas of the hood, roof, and decklid, significant damage can occur. This damage is the result of actual etching of the paint and appears as pitting or water spots. As acid rain droplets on the vehicle surface evaporate, the concentration strength of the acid increases, causing deeper and more rapid damage. This evaporation and corrosive action also occur more rapidly on dark colored cars as direct sun heat increases. It
full bulletin at NHTSA ↗Toyota vehicles are currently protected with RapgardTM protective film designed to protect the horizontal painted surfaces. This material protects from acid rain, environmental fallout, and rail contamination. Follow the Removal Procedure in this bulletin to remove the RapgardTM protective film within 90 days from initial application.
full bulletin at NHTSA ↗Vehicles may occasionally be subjected to contamination by airborne iron particles shed from railroad tracks, train wheels, exposure to heavy machinery facilities, grinding, welding, etc. This type of contamination can be identified by the presence of small, red or brown particles on the paint surface. These particles are often difficult to see on dark color paints but can be easily felt when brushing a hand across horizontal body surfaces such as the hood, roof, or deck lid. Follow the Repair Procedure in this bulletin to clean vehicles that may have been subjected to contamination by airborne iron particles such as rail dust during rail transportation or extended storage near industrial ar
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Frame rust dominates complaints on the 2006 Toyota 4Runner. Owners report severe, progressive corrosion starting from the inside of longitudinal frame rails and spreading outward—sometimes eating entirely through the metal. Rust appears most aggressive on frame bottoms, lower control arm mounts, trailing arm attachment points, and rear crossmembers. Interior frame deterioration generates thick rust chips and flakes; exterior paint blistering and clear coat peeling often precede visible holes. Several owners describe rust so advanced that frame rails become structurally compromised well before surface inspection would catch it. Components mounted to the frame—suspension brackets, fuel tank straps, brake lines, steering components, heat shields—fail as their attachment points corrode and rust-frozen fasteners become inaccessible. Multiple owners report trailing arm mounts detaching, control arm brackets separating, and subframes cracking under normal driving loads after the frame weakens from corrosion. Spare tire carriers rust in place, fuel tanks sag or drop when straps disintegrate, and brake lines rupture from internal rust. Owners note that similar-era Tundra, Sequoia, and Tacoma models received recalls for identical frame rust problems, yet the 4Runner—built on a Tacoma frame—was excluded. Dealers often refuse further service on affected vehicles citing structural safety concerns and liability risk.
Same Toyota 4Runner body reports on nearby years: 2005 · 2007
Failure modes owners describe
Longitudinal frame rail corrosion
Severe, progressive rust on the inside of driver and passenger side frame rails, starting from the bottom and spreading upward along sidewalls, generating thick rust chips (fingernail-sized to 10 sq cm pieces, up to 3mm thick). Internal corrosion cannot be seen or remediated without frame removal or inspection holes.
When: Typically visible by 12 years of age (vehicles in their mid-2010s) or as early as 76,000–96,000 miles; deterioration is cumulative and mileage-independent after initial onset.
Symptoms owners cite: Visible rust flaking or scaling from undercarriage; Holes in frame large enough to insert a finger; Frame rails weakened to the point that a tire jack punctures the bottom; Rust chips accumulating inside hollow frame sections
Repairs/costs cited: Frame replacement required; owners cite costs in thousands of dollars. Some used frames sourced from salvage yards; one owner spent approximately $7,000 for frame replacement at a body shop.
Recalls/TSBs owners mention: Toyota has recalled 2004–2010 Tacoma, Tundra, and Sequoia for identical frame rust issues. The 4Runner—built on a Tacoma platform—was excluded from recalls. Toyota states Japan-built 4Runners are not covered under U.S. recalls that apply only to U.S.-manufactured vehicles. No warranty coverage or recall program offered to 4Runner owners.
Trailing arm and lower control arm mount corrosion
Frame attachment points for suspension components (rear trailing arms, lower control arm mounts) rust through, weaken, and separate from the frame. Mounts become detached or fracture under driving loads after internal corrosion compromises structural integrity.
When: Detected during routine maintenance or after abnormal vehicle behavior; owners report onset around 76,000–127,000 miles.
Symptoms owners cite: Loud creaking or clunking noises from rear suspension; Rear of vehicle wobbles at highway speeds (30+ mph); Abnormal body roll during acceleration, braking, or bumps; Difficulty maintaining vehicle in lane; Trailing arm or control arm bracket visibly separated from frame; Vehicle fishtailing at speeds over 30 mph after rear trailing arm detaches
Repairs/costs cited: Repair requires removal and replacement of corroded mounts and affected frame sections. One owner's vehicle remained in an aftermarket body shop for over 4 months awaiting frame repair.
Recalls/TSBs owners mention: Toyota customer care provided no assistance or warranty coverage. Dealers acknowledge the problem but indicate frame and component replacement is the only solution; some dealers refuse to service vehicles with this degree of frame compromise.
Rear crossmember and subframe corrosion
Rear crossmember and subframe experience severe rust and corrosion, developing holes and weakening structural support. The rear axle becomes suspended only by remaining anchor points (some owners report only 2 of 4 mounts intact), creating a dangerous situation where the rear axle can separate from the frame.
When: Identified during maintenance or after abnormal vehicle handling; typically occurs by 110,000–150,000 miles.
Symptoms owners cite: Rear axle only attached by partial mounting points; Holes eaten through rear crossmember; Welded repair areas developing secondary holes; Vehicle declared undrivable by dealers due to structural compromise
Repairs/costs cited: Toyota has stated that replacing rear crossmember requires removing the vehicle body from the chassis—a major repair. Owners report Toyota refusing to cover this repair even after filing claims.
Recalls/TSBs owners mention: Toyota customer care denied warranty coverage, stating Japan-built vehicles are not eligible under recall programs. Body shops confirmed the issue but repair remains owner's responsibility at significant cost.
Brake line corrosion
Brake lines corrode and rupture from internal and external rust, causing complete brake fluid loss and brake failure while driving.
When: Occurs at 100,000+ miles; one owner discovered after the vehicle began losing brake fluid.
Symptoms owners cite: Complete loss of brake fluid; Brakes failed to operate properly while driving at 30 mph; Brake line visible as rusted through during inspection; Sticky brake pedal taking seconds to resume original position
Repairs/costs cited: Brake line replacement required; exact repair costs not cited in narratives.
Recalls/TSBs owners mention: No recall or warranty coverage provided.
Fuel tank strap corrosion and separation
Fuel tank mounting straps rust away from the frame, causing the fuel tank to sag, drop, or separate from the vehicle chassis during operation.
When: Detected during routine maintenance or after abnormal sounds/handling; one owner reported fuel tank straps completely rusted away by vehicle inspection.
Symptoms owners cite: Fuel tank only connected by skid plate beneath it; Fuel tank fell through frame to ground while owner was driving; Fuel tank straps inaccessible due to rust; Dangerous situation putting occupants at risk
Repairs/costs cited: Fuel tank strap replacement and potential fuel tank repair/replacement required.
Recalls/TSBs owners mention: No recall or warranty coverage indicated.
Suspension fastener and bracket corrosion
Nuts, bolts, brackets, and fasteners attaching suspension and other undercarriage components to the frame rust and corrode to the point where their structural integrity is significantly diminished. Components can fail, break, or become inaccessible for service.
When: Progressive onset; owners note this issue accumulating over years of ownership.
Symptoms owners cite: Fasteners completely rusted and unable to be removed or replaced; Components hanging off the frame or partially detached; Parts failing despite vehicle being well-maintained; Repair shops unable to access or service components due to rust
Repairs/costs cited: Replacement of rusted fasteners and brackets; some shops refuse to attempt service due to corrosion severity and liability concerns.
Recalls/TSBs owners mention: No manufacturer support or warranty coverage.
Motor mount bracket fracture
Bracket holding the motor mount rusted and fractured, causing the motor to shift and strike the differential, rupturing the upper engine oil pan. May be related to rust/corrosion or a design weakness that was reinforced in 2007 and later models.
When: One reported incident at an unspecified mileage; appears to be an isolated case from the narratives provided.
Symptoms owners cite: Motor strikes the differential; Upper engine oil pan ruptures; Broken or fractured motor mount bracket visible in frame
Repairs/costs cited: Oil pan replacement and motor mount bracket repair required; one owner provided photos of the failure.
Recalls/TSBs owners mention: Design was reinforced in 2007 and later models, suggesting Toyota acknowledged the weakness.
Spare tire carrier and hitch corrosion
Spare tire carrier assembly and trailer hitch attachment rusts, making it impossible to secure the spare tire or safely use the hitch. Rust prevents installation of replacement carriers or use of the hitch due to structural compromise and safety hazard.
When: Detected when attempting to install spare tire or use hitch.
Symptoms owners cite: Spare tire cannot be secured to corroded carrier; Carrier would fall off during transport if spare were installed; Hitch will fall off if towing is attempted; Rust and corrosion render attachment points unsafe
Repairs/costs cited: Spare tire stored inside vehicle or replaced carrier cannot be used. Trailer hitch unusable; one dealer attempted to replace the carrier assembly but was unable to complete the repair.
Recalls/TSBs owners mention: No recall or warranty coverage.
Tailgate interior corrosion and rot
Interior sound-deadening material on the tailgate retains moisture, causing the metal to rot from the inside out. Paint blistering is often the first visible sign; over time, rust perforates the tailgate.
When: Paint blistering observed after approximately 2 years of ownership; full rust-through occurs over several years.
Symptoms owners cite: Paint blistering on tailgate exterior; Rust originating from inside the tailgate; Rust perforation through the tailgate metal; Clear coat peeling
Repairs/costs cited: Body shop repair or tailgate replacement required; one owner noted this is a known common problem among 2006 4Runners.
Recalls/TSBs owners mention: No recall or warranty coverage; one Toyota dealership stated the vehicle was out of warranty and could not assist.
Exterior paint deterioration and clear coat failure
Original factory paint gradually deteriorates, with clear coat peeling and paint completely fading across the body. Deterioration is progressive and occurs despite proper vehicle care.
When: Begins around 2014 (approximately 8 years into ownership) on one vehicle; another owner reported clear coat peeling starting around the same timeframe.
Symptoms owners cite: Clear coat completely peeling off; Paint completely faded on most body parts; Brown rust spots visible on body; Whole body requiring a new paint job
Repairs/costs cited: Complete repaint or clear coat restoration required; costs not specified.
Recalls/TSBs owners mention: No recall or warranty coverage.
Roof rubber strip adhesion failure
Rubber weatherstripping or sealant along the roofline fails and detaches, causing the strip to become a flying hazard, particularly in car washes.
When: One incident reported during car wash with air dryer; mileage not specified.
Symptoms owners cite: Rubber strip comes flying off during car wash; Loud thumping sound on roof; Strip becomes a projectile hazard
Repairs/costs cited: Roof strip replacement and reattachment required; cost not specified.
Recalls/TSBs owners mention: No response indicated.
Synthesized from 115 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 9 most recent
The contact owns a 2006 Toyota 4Runner. The contact stated that after a State Inspection, the vehicle was declared unsafe to drive on the State roadways due to severe corrosion. The contact stated no warning light was illuminated. The contact had taken the vehicle to a local dealer, where it was diagnosed and determined that the subframe needed to be replaced due to extensive corrosion. The…
St last year, Toyota settled a class-action lawsuit involving approximately 1.5 million tacoma, tundra and sequoia trucks also built on a frame1 ' Toyota agreed to inspect and replace the frames at an estimated cost of $3.4 billion. This confirms frame corrosion is a problem well-known to Toyota and the public.
Structural - frame rust. Toyota has not recalled the 4runner due to frame rust experienced on the tacoma. Attached are pictures of underbody. This vehicle would not pass inspection and I am located in california where laws are strict.
During recent maintenance of my 2006 Toyota 4runner with 115k miles, a mechanic notified me that the frame crossmember in front which attaches to the control arms was completely rusted through and was a significant safety concern. The vehicle was brought to the Toyota dealer to assess condition of the frame. The dealer stated the frame was irreparable and was not covered by a recent Toyota…
The vehicle was purchased on 01/26/2017 and was driven in upstate new york until 1/1/2018 when I relocated to my current address in south carolina for my new career. The frame of my Toyota 4runner is severely rusting causing the structural integrity of the vehicle to be compromised and causing dangerous damage to steering, brake, suspension, fuel components throughout the vehicle on their…
I own a 2006 Toyota 4Runner Sport and have major rust issue with the frame of vehicle. Toyota is aware of this issue and I believe it is a safety hazard. No way should it rust like it has.
2006 4runner with 165k miles will not pass inspection due to excessive frame rust. I purchased this brand new from the dealer and have taken excellent care of it. There is no rust on the body. The rust is excessive for other similar vehicles from other manufactures. Toyota has replaced similar frames on their tacoma models but have done nothing for 2006 4runner owners.
Tl* the contact owns a 2006 Toyota 4runner. The contact stated that the vehicle's structure was flaking and metal had detached from the frame onto the driveway. The vehicle was taken to an independent mechanic for routine maintenance who determined that the undercarriage was rusted. The local dealer and manufacturer were not contacted. The failure mileage was 85,000.
Tl* the contact owns a 2006 Toyota 4runner. The contact noticed excessive rust on the frame of the vehicle. The manufacturer was made aware of the issue. The vehicle was not repaired. The approximate failure mileage was 100,762.
Had body trouble with your 2006 Toyota 4Runner?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the body problem on the 2006 Toyota 4Runner?
It's a documented issue but not catastrophic. 115 complaints have been filed. Repairs average $1,500 and most owners catch it before it causes a breakdown.
At what mileage does the body typically fail?
Across the 78 complaints that reported odometer mileage, most body failures cluster between 90,000 and 165,000 miles, with the median around 126,000. A quarter of owners report trouble before 90,000; a quarter make it past 165,000. Maintenance history matters more than the odometer alone — this is the reported failure window, not a guarantee.
What does it cost to fix?
Independent shops typically charge around $1,500 for body repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to body?
No active recalls currently cover body issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2006/Toyota/4Runner.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.