2018 Toyota 4Runner Problems: 5 Issues Every Owner Should Know

2018 model year · 4,207+ owner reports · Updated April 2026

According to Au7o's analysis of 4,207+ owner reports, the 2018 Toyota 4Runner has 5 documented known issues, with 1 rated critical. The most serious is Frame Rust and Corrosion ($200-$15,000 repair). The most commonly reported issue is Frame Rust and Corrosion with 1,654 owner reports. Across all issues, repair costs range from $50 to $15,000. DIY maintenance guides at au7o.io.

All 5 Known Issues

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Community Reported

1,654 owners

On the 2010-2019 Toyota 4Runner, the frame on 4Runners, especially in northern/salt belt states, can develop severe rust and corrosion. This is a safety concern as the frame provides structural integrity. Toyota had a frame replacement program for some Tacomas/Tundras but 4Runners were not included.

This issue also affects: BMW 8 Series, BMW i3, BMW M3

Common Symptoms

Visible rust on frame rails
Rust flakes falling when driving
Holes developing in frame
Suspension mounts rusted
Failed inspection due to frame

How to Fix

Prevention: Apply Fluid Film or similar undercoating annually, especially before winter. Wash undercarriage regularly to remove salt. For existing rust: Wire brush loose rust, apply rust converter like POR-15, then undercoat. Severe cases may require frame section replacement ($2,000-5,000) or frame swap ($8,000-15,000).

What Owners Are Using

Parts and tips from 1,654+ owners who fixed this issue

TipDIY repairs can save significantly - dealer charges $2,000-5,000 but DIY costs are typically 50-70% less
TipPrevention: Apply Fluid Film or similar undercoating annually, especially before winter.
NoteThis is a high-severity issue - ignoring it can lead to costly repairs or safety concerns. Address it promptly.
TipGet a proper diagnosis before replacing parts - similar symptoms can have different causes
UpgradePOR-15 rust preventive coating stops rust permanently (POR-15 Rust Preventive Coating)
View on Amazon
UpgradeRust-Oleum rust converter spray for treating corroded panels (Rust-Oleum Rust Converter Spray)
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Typical repair cost:$200 - $15,000

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1,654+ owners have reported this issue

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Community Reported

High Confidence1,654 reportsLast reported by owners Feb 2024Reviewed Feb 2026

Community Reported

876 owners

On the 2010-2023 Toyota 4Runner, the KDSS hydraulic suspension system can develop leaks at the hydraulic lines and accumulators, especially in areas with road salt. The system helps reduce body roll on-road while allowing articulation off-road. Corrosion of the KDSS lines is common in northern states.

Common Symptoms

Hydraulic fluid leaking under front/rear
KDSS warning light on dash
Poor handling or excessive body roll
Clicking from front suspension
Visible corrosion on KDSS lines

How to Fix

Inspect KDSS lines annually for corrosion. Apply rust protectant to exposed lines. For leaking accumulators: Replace with new units ($300-600 each). Hydraulic line leaks require line replacement. Some owners delete KDSS entirely and install conventional sway bars ($500-1,500). Full KDSS repair at dealer: $1,500-4,000.

What Owners Are Using

Parts and tips from 876+ owners who fixed this issue

TipDIY repairs can save significantly - dealer charges $300-600 but DIY costs are typically 50-70% less
TipGet a proper diagnosis before replacing parts - similar symptoms can have different causes
TipSearch Toyota 4Runner forums and owner groups for real-world experiences and DIY guides
TipGet multiple quotes from independent mechanics - dealer prices can be 2-3x higher for the same repair
UpgradeComplete strut and shock absorber set for full suspension refresh (KYB Excel-G Strut/Shock Set)
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UpgradeFour-wheel alignment kit with cam bolts for proper tire wear correction (Moog Alignment Cam Bolt Kit)
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Typical repair cost:$300 - $4,000

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876+ owners have reported this issue

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Community Reported

High Confidence876 reportsLast reported by owners Feb 2024Reviewed Feb 2026

Community Reported

678 owners

On the 2010-2023 Toyota 4Runner, a clunk or pop may be heard from the steering column area when turning the wheel, especially at low speeds or when going from left to right. The issue is typically the intermediate steering shaft or worn rack bushings. Common on vehicles driven off-road.

Common Symptoms

Clunk when turning wheel at low speed
Pop when turning from stop
Noise from steering column area
Play in steering wheel

How to Fix

For intermediate shaft noise: Lubricate the shaft splines with white lithium grease (temporary fix) or replace shaft ($200-400). For steering rack clunk: Tighten rack mounting bolts or replace rack bushings. Full rack replacement if worn ($800-1,500). Have alignment checked after any steering work.

What Owners Are Using

Parts and tips from 678+ owners who fixed this issue

TipDIY repairs can save significantly - dealer charges $200-400 but DIY costs are typically 50-70% less
TipGet a proper diagnosis before replacing parts - similar symptoms can have different causes
TipSearch Toyota 4Runner forums and owner groups for real-world experiences and DIY guides
TipGet multiple quotes from independent mechanics - dealer prices can be 2-3x higher for the same repair
UpgradePolyurethane bushing kit for longer life and tighter handling than OEM rubber (Energy Suspension Bushing Kit)
View on Amazon
UpgradeSway bar end links to eliminate clunking over bumps (Moog Sway Bar Link Kit)
View on Amazon

Typical repair cost:$50 - $1,500

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678+ owners have reported this issue

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Community Reported

High Confidence678 reportsLast reported by owners Feb 2024Reviewed Feb 2026

Community Reported

432 owners

On the 2010-2022 Toyota 4Runner, the A/C compressor can fail prematurely, often sending metal debris throughout the system. When the compressor fails, the entire A/C system typically needs to be flushed and the condenser, drier, and expansion valve replaced along with the compressor to prevent repeat failure.

Common Symptoms

A/C not cooling
Clicking or grinding from compressor
A/C clutch not engaging
Metal shavings in refrigerant
Burning smell when A/C on

How to Fix

If compressor fails with debris: Replace compressor, condenser, drier/accumulator, and expansion valve. Flush all lines. Use only OEM or Denso compressor for reliability. Cost: $1,200-2,000 at shop. Preventive: Run A/C for a few minutes monthly even in winter to keep seals lubricated.

What Owners Are Using

Parts and tips from 432+ owners who fixed this issue

TipDIY repairs can save significantly - dealer charges $1,200-2,000 but DIY costs are typically 50-70% less
TipPreventive: Run A/C for a few minutes monthly even in winter to keep seals lubricated.
TipConsider OEM parts for critical components like sensors and electrical parts - aftermarket can be unreliable
TipGet a proper diagnosis before replacing parts - similar symptoms can have different causes
UpgradePrestone coolant flush kit for complete cooling system service (Prestone Coolant Flush Kit)
View on Amazon
UpgradeStant thermostat — preventive replacement during coolant service (Stant Thermostat)
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Typical repair cost:$1,200 - $2,500

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432+ owners have reported this issue

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Community Reported

Medium Confidence432 reportsLast reported by owners Feb 2024Reviewed Feb 2026

Community Reported

567 owners

On the 2014-2019 Toyota 4Runner, some 5th gen 4Runners develop a whining noise from the rear differential, especially noticeable at highway speeds (40-60 mph). The noise is often related to differential gear setup from factory or premature bearing wear.

Common Symptoms

Whining at highway speeds
Humming from rear of vehicle
Noise changes with acceleration/deceleration
Noise disappears when coasting in neutral

How to Fix

Change differential fluid to Toyota OEM gear oil - some owners report this reduces noise. If noise persists, a differential fluid additive like Lucas LSD may help ($15). For severe cases, differential rebuild or replacement ($1,500-3,000) may be needed. Have a shop check pinion preload and backlash settings.

What Owners Are Using

Parts and tips from 567+ owners who fixed this issue

TipDIY repairs can save significantly - dealer charges $1,500-3,000 but DIY costs are typically 50-70% less
TipConsider OEM parts for critical components like sensors and electrical parts - aftermarket can be unreliable
TipGet a proper diagnosis before replacing parts - similar symptoms can have different causes
UpgradeRoyal Purple Max-Gear differential fluid for superior protection (Royal Purple Max-Gear Differential Fluid)
View on Amazon
UpgradeDorman differential cover gasket — direct OE replacement (Dorman Differential Cover Gasket)
View on Amazon

Typical repair cost:$100 - $3,000

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567+ owners have reported this issue

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Community Reported

Medium Confidence567 reportsLast reported by owners Feb 2024Reviewed Feb 2026

Frequently Asked Questions

What are the most common Toyota 4Runner problems?

According to Au7o's analysis of 4,207+ owner reports, the 2018-2018 Toyota 4Runner has 5 documented issues. The most frequently reported are: Frame Rust and Corrosion, KDSS (Kinetic Dynamic Suspension System) Leaks/Corrosion, A/C Compressor Failure. Of these, 1 is rated critical and should be addressed promptly.

Is the Toyota 4Runner reliable?

The 2018-2018 Toyota 4Runner has 5 known issues documented across 4,207+ owner reports. 1 issue is rated critical: Frame Rust and Corrosion. Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common Toyota 4Runner problems?

Repair costs for known Toyota 4Runner issues range from $50 to $15,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Frame Rust and Corrosion, typically costs $200-$15,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What is the 2010-2019 Toyota 4Runner Frame Rust and Corrosion?

The frame on 4Runners, especially in northern/salt belt states, can develop severe rust and corrosion. This is a safety concern as the frame provides structural integrity. Toyota had a frame replacement program for some Tacomas/Tundras but 4Runners were not included. Repairs typically run $200-$15,000. Severity: high.

What is the 2010-2023 Toyota 4Runner KDSS (Kinetic Dynamic Suspension System) Leaks/Corrosion?

The KDSS hydraulic suspension system can develop leaks at the hydraulic lines and accumulators, especially in areas with road salt. The system helps reduce body roll on-road while allowing articulation off-road. Corrosion of the KDSS lines is common in northern states. Repairs typically run $300-$4,000. Severity: medium.

What is the 2010-2022 Toyota 4Runner A/C Compressor Failure?

The A/C compressor can fail prematurely, often sending metal debris throughout the system. When the compressor fails, the entire A/C system typically needs to be flushed and the condenser, drier, and expansion valve replaced along with the compressor to prevent repeat failure. Repairs typically run $1,200-$2,500. Severity: medium.

What is the 2010-2023 Toyota 4Runner Steering Rack Clunk / Intermediate Shaft Noise?

A clunk or pop may be heard from the steering column area when turning the wheel, especially at low speeds or when going from left to right. The issue is typically the intermediate steering shaft or worn rack bushings. Common on vehicles driven off-road. Repairs typically run $50-$1,500. Severity: low.

What is the 2014-2019 Toyota 4Runner Rear Differential Noise/Whine?

Some 5th gen 4Runners develop a whining noise from the rear differential, especially noticeable at highway speeds (40-60 mph). The noise is often related to differential gear setup from factory or premature bearing wear. Repairs typically run $100-$3,000. Severity: low.

2018 Toyota 4Runner Problems: 5 Issues Every Owner Should Know

All 5 Known Issues

2010-2019 Toyota 4Runner: Frame Rust and Corrosion#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

2010-2023 Toyota 4Runner: KDSS (Kinetic Dynamic Suspension System) Leaks/Corrosion#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

2010-2023 Toyota 4Runner: Steering Rack Clunk / Intermediate Shaft Noise#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

2010-2022 Toyota 4Runner: A/C Compressor Failure#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

2014-2019 Toyota 4Runner: Rear Differential Noise/Whine#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

Other Toyota Models

Frequently Asked Questions

What are the most common Toyota 4Runner problems?

Is the Toyota 4Runner reliable?

How much does it cost to fix common Toyota 4Runner problems?

What is the 2010-2019 Toyota 4Runner Frame Rust and Corrosion?

What is the 2010-2023 Toyota 4Runner KDSS (Kinetic Dynamic Suspension System) Leaks/Corrosion?

What is the 2010-2022 Toyota 4Runner A/C Compressor Failure?

What is the 2010-2023 Toyota 4Runner Steering Rack Clunk / Intermediate Shaft Noise?

What is the 2014-2019 Toyota 4Runner Rear Differential Noise/Whine?