The MOT Files

Known faults, from the test record

Lexus RX400H common problems

What fails on the Lexus RX400H at MOT, which parts are behind it, and how each model year compares. From 6,753 DVSA test records.

Data updated

Quick answer

The Lexus RX400H's most common MOT problems are suspension bushes, bulbs and lamps, tyres, recorded in 46.3%, 41.0% and 24.1% of failed tests respectively. By model year, 2009 cars pass most often (72.2%) and 2006 cars least (67.4%), though most of that gap is age. Every figure here is what testers recorded, not what owners reported.

A “common problems” list is usually a forum thread: whoever had the worst day writes the longest post. This one is built the other way, from every Lexus RX400H that took an MOT last year and what the tester wrote down. It cannot see breakdowns, electrical gremlins or a gearbox that hunts, because the test does not check those. What it can see, it sees across 6,753 cars.

By component

What wears out on a RX400H

Failure items grouped by the part behind them, with the share of failed Lexus RX400H tests recording each. A part can carry several DVSA wordings; they are listed beneath. One failed test often lists several items, so shares do not sum to 100%.

  1. 1.Suspension bushes

    46.3% of failed tests

    Rubber bushes in arms and links perish and split with age and load; the most recorded suspension item on the test.

    • “A suspension joint dust cover missing or no longer prevents the ingress of dirt etc” — explained12.8%
    • “A suspension pin, bush or joint excessively worn” — explained10.2%
    • “A suspension joint dust cover missing or no longer prevents the ingress of dirt etc” — explained6.3%
    • “A suspension joint dust cover missing or no longer prevents the ingress of dirt etc” — explained5.6%

    Across all cars, suspension bushes failures climb 20-fold between three and fifteen years, peaking at 15+ years. How long suspension bushes last

  2. 2.Bulbs and lamps

    41.0% of failed tests

    Filament bulbs simply expire; the cheapest and most avoidable failure on the test, and one of the most recorded.

    • “A lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning” — explained22.5%
    • “A rear registration plate lamp or light source missing or inoperative in the case of a single lamp or all lamps” — explained6.0%
    • “A headlamp or light source missing, inoperative or more than ½ not functioning in the case of LED” — explained5.0%
    • “Headlamp levelling device inoperative” — explained4.7%

    Across all cars, bulbs and lamps failures climb 15-fold between three and fifteen years, peaking at 15+ years. How long bulbs and lamps last

  3. 3.Tyres

    24.1% of failed tests

    Tread wears with every mile and sidewalls age and take kerb damage; the legal minimum is 1.6 mm across the central three-quarters.

    • “Tyre tread depth not in accordance with the requirements” — explained10.9%
    • “A tyre seriously damaged” — explained6.6%
    • “A tyre cords visible or damaged” — explained6.5%

    Across all cars, tyres failures run at a similar rate at every age, because they are replaced on a cycle rather than wearing out with the car. How long tyres last

  4. 4.Parking brake

    19.0% of failed tests

    Cables stretch and seize, rear shoes and adjusters wear; efficiency is measured on the roller tester against the vehicle's weight.

    • “Parking brake efficiency below minimum requirement” — explained7.6%
    • “Parking brake efficiency less than 50% of the required value” — explained4.7%
    • “Parking brake inoperative on one side” — explained4.6%
    • “Parking brake efficiency below minimum requirement” — explained2.2%

  5. 5.Suspension arms and mountings

    14.1% of failed tests

    Arms bend on impact and mountings corrode into the body; a corroded mounting is a structural item and fails as one.

    • “The strength or continuity of the load bearing structure within 30cm of any sub-frame, spring or suspension component mounting (a 'prescribed area') is significantly reduced or inadequately repaired” — explained11.0%
    • “A suspension component excessively damaged or corroded” — explained3.1%

  6. 6.Headlamp aim

    11.4% of failed tests

    Aim drifts with sagging suspension, a knocked lamp or a botched bulb change; adjustment, not a part.

    • “The aim of a headlamp is not within limits laid down in the requirements” — explained4.2%
    • “The aim of a headlamp is not within limits laid down in the requirements” — explained4.0%
    • “The aim of a headlamp is not within limits laid down in the requirements” — explained3.2%

  7. 7.Wiper blades and washers

    10.3% of failed tests

    Rubber blades harden and split within a year or two; washer jets block and pumps fail.

    • “Wiper blade missing or obviously not clearing the windscreen” — explained7.7%
    • “Windscreen washers not working or not providing sufficient fluid to clear the windscreen” — explained2.5%

    Across all cars, wiper blades and washers failures run at a similar rate at every age, because they are replaced on a cycle rather than wearing out with the car. How long wiper blades and washers last

  8. 8.Shock absorbers

    8.2% of failed tests

    Seals wear and the damper leaks fluid or loses its action; failure is for a leak or no damping, not for being tired.

    • “A shock absorber damaged to the extent that it does not function or showing signs of severe leakage” — explained8.2%

    Across all cars, shock absorbers failures climb 7-fold between three and fifteen years, peaking at 15+ years. How long shock absorbers last

By registration year

RX400H problems by year

MOT pass rate for Lexus RX400H cars by the year they were first registered, from years with at least 1,000 tests. Every car in a row is the same age, so the rate is raw. Neighbouring years differ by a year of wear — a step of a point or two is age. No single step here is large enough to point at a generation change.

200667%
200769%+1.3
200871%+2.2
200972%+1.3

Last column: change on the previous year, in points. Years registered within the last three years have not yet been tested and are not shown.

Before it fails

What testers warn RX400H owners about

Advisories are the same parts a year or two earlier. Share of all Lexus RX400H tests carrying an advisory for each.

Go deeper

The rest of the RX400H file

Common questions

What are the most common problems with a Lexus RX400H?
Going by what fails the MOT, suspension bushes (recorded in 46.3% of failed tests), bulbs and lamps (recorded in 41.0% of failed tests), and tyres (recorded in 24.1% of failed tests). These are the items testers actually record across 6,753 tests, not reports from owners, so they describe what goes wrong at the point where it has to be fixed.
Which Lexus RX400H year is the most reliable?
By MOT pass rate, Lexus RX400H cars registered in 2009 do best at 72.2% and 2006 cars do worst at 67.4%. Most of that ordering is simply age — newer cars pass more — so read the year table for steps larger than a couple of points between neighbouring years; those mark a change in the cars rather than the calendar.
Is the Lexus RX400H reliable?
The Lexus RX400H passes 69.0% of MOTs unadjusted; its fleet is too narrow in age or mileage for a fair national comparison. An MOT measures roadworthiness on the day rather than breakdowns or running costs, so this is a reliability measure in the narrow sense: how often the car meets the legal standard, and what stops it.
What should I check when buying a used Lexus RX400H?
Start with what fails most: suspension bushes, bulbs and lamps, tyres. Then read the car's own MOT history for advisories carried year to year without repair — the model tells you what to expect, the history tells you whether this owner dealt with it.

Analysis built from DVSA data of