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Lexus Ls400 Problems & Known Issues

The most common Lexus Ls400 problems ranked by severity — what to watch for, what it costs to fix, and what happens if you ignore it.

Generations

UCF10 — First Generation
1990–1994
4.0L V8
UCF20 — Second Generation
1995–2000
4.0L V8

Top issues to watch for

The most serious Lexus Ls400 problems ranked by severity. We track 5 known issues — here are the ones you need to know about first.

Dangerous
Vehicle structure corrosion reducing assembly rigidity
UCF10, UCF201990–2000120k–250k miles
The LS400 suffers from significant structural corrosion that reduces the rigidity of the vehicle assembly, particularly around suspension mounting points and the rear subframe area. This affects cars from 120,000 miles onwards and represents a safety-critical structural weakness. The issue is progressive and worsens with age, making thorough inspection essential on higher-mileage examples.
What happens if ignoredStructural corrosion that compromises assembly rigidity is an MOT failure and makes the vehicle unsafe to drive. Repair typically requires extensive welding work by a specialist fabricator. Costs can range from £1,500 for localised repairs to £4,000+ for complete subframe reconstruction, often exceeding the vehicle's value.
Independent garage
£1,500–£4,000
Specialist
£2,000–£5,000
Parts only
£200–£800
Dangerous
Suspension mounting point corrosion
UCF10, UCF201990–200080k–250k miles
Corrosion around suspension mounting points represents a critical safety issue on the LS400, with the load-bearing structure within 30cm of suspension component mountings deteriorating significantly above fleet average rates. This affects the fundamental structural integrity needed to safely support suspension loads during driving, braking, and cornering. The issue progressively worsens and can lead to suspension component detachment.
What happens if ignoredCorroded suspension mounting points can fail catastrophically, causing loss of vehicle control, wheel detachment, or suspension collapse. This is an immediate MOT failure and the vehicle should not be driven. Professional structural repair or replacement is mandatory, typically costing £2,000-£6,000 depending on the extent of damage.
Independent garage
£2,000–£5,000
Specialist
£2,500–£6,000
Parts only
£300–£1,000
Major
Power steering system fluid leaks and pump failure
UCF10, UCF201990–200080k–200k miles
The LS400 has a documented pattern of power steering system failures, with the hydraulic pump and associated seals failing at significantly higher rates than the fleet average. This affects vehicles from 80,000 miles onwards and can result in complete loss of power assistance. The system runs at high pressure and component deterioration is accelerated by age and contaminated fluid.
What happens if ignoredComplete power steering failure makes the car extremely difficult to steer, especially at low speeds or when parking. A failing pump can also contaminate the entire system with metal debris, requiring replacement of the rack and all fluid lines. Total system replacement costs £1,500-£2,500.
Independent garage
£400–£800
Specialist
£600–£1,200
Main dealer
£800–£1,500
Parts only
£300–£600
Major
Suspension bushes and joint excessive wear
UCF10, UCF201990–200080k–200k miles
The LS400 suffers from accelerated wear of suspension bushes and joints, failing at 7.6 times the fleet average rate. The heavy V8 engine and luxury car weight place additional stress on suspension components, while the rubber bushes deteriorate with age regardless of mileage. This affects ride quality, handling precision, and can cause MOT failures. Multiple bushes typically need replacement together as they age as a system.
What happens if ignoredWorn suspension bushes compromise handling, increase braking distances, and cause premature tyre wear. Multiple bush failures often occur together, requiring comprehensive suspension rebuilding. An MOT failure is likely once wear reaches the legal limit. Complete suspension refresh typically costs £800-£1,500.
Independent garage
£400–£800
Specialist
£600–£1,200
Main dealer
£800–£1,500
Parts only
£200–£500

1 more known issues tracked

Including wear items, electrical niggles, and generation-specific problems. Check a specific car to see which issues apply to its age and mileage.

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MOT failure hotspots

Based on DVSA MOT test data. These are the items where the Lexus Ls400 fails at a significantly higher rate than the average car.

Suspension pin, bush or joint worn
Suspension · 80-100k miles
MOT failure rate: 29x the fleet average
Sample: 257 tests
Power steering fault
Steering · 80-100k miles
MOT failure rate: 25x the fleet average
Sample: 382 tests
Emissions failure
Exhaust & Emissions · 150k+ miles
MOT failure rate: 14x the fleet average
Sample: 1,533 tests
Fluid leak
Exhaust & Emissions · 120-150k miles
MOT failure rate: 13x the fleet average
Sample: 483 tests
Exhaust system damage
Bodywork · 150k+ miles
MOT failure rate: 11x the fleet average
Sample: 2,021 tests
Structural corrosion
Bodywork · 120-150k miles
MOT failure rate: 11x the fleet average
Sample: 816 tests

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Related

Lexus Ls400 reliability FAQs

What are the most common problems with the Lexus Ls400?

The Lexus Ls400 has 5 known issues across 3 severity levels. The most serious are: Vehicle structure corrosion reducing assembly rigidity, Suspension mounting point corrosion.

Is the Lexus Ls400 reliable?

The Lexus Ls400 has 2 dangerous and 2 major known issues. Most can be avoided with a thorough pre-purchase check and full service history.

How much does it cost to fix Lexus Ls400 problems?

Repair costs range widely. The most significant issue (Vehicle structure corrosion reducing assembly rigidity) costs £1,500–£4,000 at an independent garage. Minor issues can be under £200. Always get a full inspection before buying.

Which Lexus Ls400 generation is most reliable?

The UCF10 (1990–1994) has the fewest dangerous issues (2). However, condition and service history matter more than generation — a well-maintained earlier car can be more reliable than a neglected newer one.