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Getting through the MOT

Most MoT failures are due to something quite simple, such as a blown light bulb or a worn out windscreen wiper blade. Putting everything right before the test will save the inconvenience and expense of a re-test. It will also be a lot cheaper than paying garage labour rates for things you can do yourself.

We show you how to check your car before you put it in for the test. If there is anything wrong, you'll find help on how to fix basic problems as well as more involved issues look in the appropriate Haynes Service and Repair Manual for your car.

It has only been possible to summarise the test requirements here, based on the regulations in force at the time of publication. Test standards are becoming increasingly stringent, although in some cases there are exemptions for older vehicles.

The help of an assistant will be necessary to carry out these checks thoroughly. The checks have been sub-divided into four categories. Please click on a category heading for details on the checks.

Step 1 Handbrake
  • Test the operation of the handbrake. Excessive travel (too many clicks) indicates incorrect brake or cable adjustment.
  • Check that the handbrake cannot be released by tapping the lever sideways.
  • Check the security of the lever mountings.
Step 2 Footbrake
  • Depress the brake pedal and check that it does not creep down to the floor, indicating a master cylinder fault. Release the pedal, wait a few seconds, then depress it again. If the pedal travels nearly to the floor before firm resistance is felt, brake adjustment or repair is necessary. If the pedal feels spongy, there is air in the hydraulic system which must be removed by bleeding.
  • Check that the brake pedal is secure and in good condition. Check also for signs of fluid leaks on the pedal, floor or carpets, which would indicate failed seals in the brake master cylinder.
  • Check the servo unit (when applicable) by operating the brake pedal several times, then keeping the pedal depressed and starting the engine. As the engine starts, the pedal will move down slightly. If not, the vacuum hose or the servo itself may be faulty.
Step 3 Steering wheel and column
  • Examine the steering wheel for fractures or looseness of the hub, spokes or rim.
  • Move the steering wheel from side to side and then up and down.
  • Check that the steering wheel is not loose on the column, indicating wear or a loose retaining nut. 
  • Continue moving the steering wheel as before, but also turn it slightly from left to right.
  • Check that the steering wheel is not loose on the column, and that there is no abnormal movement of the steering wheel, indicating wear in the column support bearings or couplings.
Step 4 Windscreen and mirrors
  • The windscreen must be free of cracks or other significant damage within the driver's field of view (small stone chips are acceptable).
  • Rear view mirrors must be secure, intact, and capable of being adjusted.
Step 5 Seat belts and seats

The following checks are applicable to all seat belts, front and rear:

  • Examine the webbing of all the belts (including rear belts if fitted) for cuts, serious fraying or deterioration. Fasten and unfasten each belt to check the buckles. If applicable, check the retracting mechanism. Check the security of all seat belt mountings accessible from inside the vehicle.
  • The front seats themselves must be securely attached and the backrests must lock in the upright position.
Step 6 Doors
  • Both front doors must be able to be opened and closed from outside and inside, and must latch securely when closed.
Step 7 Vehicle identification
  • Number plates must be in good condition, secure and legible, with letters and numbers correctly spaced - spacing at (B) should be twice that at (A).
  • The VIN plate and/or homologation plate must be legible.

Step 8 Electrical equipment
  • Switch on the ignition and check the operation of the horn.
  • Check the windscreen washers and wipers, examining the wiper blades; renew damaged or perished blades. Also check the operation of the stoplights.
  • Check the operation of the sidelights and number plate lights. The lenses and reflectors must be secure, clean and undamaged.
  • Check the operation and alignment of the headlights. The headlight reflectors must not be tarnished and the lenses must be undamaged.
  • Switch on the ignition and check the operation of the direction indicators (including the instrument panel tell-tale) and the hazard warning lights. Operation of the sidelights and stop-lights must not affect the indicators - if it does, the cause is usually a bad earth at the rear light cluster.
  • Check the operation of the rear fog light(s), including the warning light on the instrument panel or in the switch.
  • The ABS and airbag warning lights (as applicable) must operate as specified by the car maker. This usually means lighting up when the ignition is switched on, then going out and staying out.
Step 9 Footbrake
  • Examine the master cylinder, brake pipes and servo unit for leaks, loose mountings, corrosion or other damage.
  • The fluid reservoir must be secure and the fluid level must be between the upper (MAX) and lower (MIN) markings.
  • Inspect both front brake flexible hoses for cracks or deterioration of the rubber. Turn the steering from lock to lock, and ensure that the hoses do not contact the wheel, tyre, or any part of the steering or suspension mechanism. With the brake pedal firmly depressed, check the hoses for bulges or leaks under pressure.
Step 10 Steering and suspension
  • Have your assistant turn the steering wheel from side to side slightly, up to the point where the steering gear just begins to transmit this movement to the roadwheels. Check for excessive free play between the steering wheel and the steering gear, indicating wear or insecurity of the steering column joints, the column-to-steering gear coupling, or the steering gear itself.
  • Have your assistant turn the steering wheel more vigorously in each direction, so that the roadwheels just begin to turn. As this is done, examine all the steering joints, linkages, fittings and attachments. Renew any component that shows signs of wear or damage. On vehicles with power steering, check the security and condition of the steering pump, drivebelt and hoses.
  • Check that the vehicle is standing level, and at approximately the correct ride height.
Step 11 Shock absorbers
  • Depress each corner of the vehicle in turn, then release it. The vehicle should rise and then settle in its normal position. If the vehicle continues to rise and fall, the shock absorber is defective.
  • A shock absorber which has seized will also cause the vehicle to fail.
Step 12 Exhaust system
  • Start the engine. With your assistant holding a rag over the tailpipe, check the entire system for leaks. Repair or renew leaking sections.
  • Jack up the front and rear of the vehicle, and securely support it on axle stands. Position the stands clear of suspension assemblies. Ensure that the wheels are clear of the ground and that the steering can be turned from lock to lock.
Step 13 Steering mechanism
Step 14 Front and rear suspension and wheel bearings
  • Starting at the front right-hand side, grasp the road-wheel at the 3 o'clock and 9 o'clock positions and shake it vigorously.
  • Check for free play or insecurity at the wheel bearings, suspension balljoints, or suspension mountings, pivots and attachments.
  • Now grasp the wheel at the 12 o'clock and 6 o'clock positions and repeat the previous inspection. Spin the wheel, and check for roughness or tightness of the front wheel bearing.
  • If excess free play is suspected at a component pivot point, this can be confirmed by using a large screwdriver or similar tool and levering between the mounting and the component attachment. This will confirm whether the wear is in the pivot bush, its retaining bolt, or in the mounting itself (the bolt holes can often become elongated).
  • Carry out all the above checks at the other front wheel, and then at both rear wheels.
Step 15 Springs and shock absorbers
  • Examine the suspension struts (when applicable) for serious fluid leakage, corrosion, or damage to the casing. Also check the security of the mounting points.
  • If coil springs are fitted, check that the spring ends locate correctly in their seats, and that the spring is not badly corroded, cracked or broken.
  • If leaf springs are fitted, check that all leaves are intact, that the axle is securely attached to each spring, and that there is no deterioration of the spring eye mountings, bushes, and shackles.
  • The same general checks apply to vehicles fitted with other suspension types, such as torsion bars, hydraulic displacer units, etc. Ensure that all mountings and attachments are secure, that there are no signs of excessive wear, corrosion or damage, and (on hydraulic types) that there are no fluid leaks or damaged pipes.
  • Inspect the shock absorbers for signs of serious fluid leakage. Check for wear of the mounting bushes or attachments, or damage to the body of the unit.
Step 16 Driveshafts (fwd vehicles only)
  • Rotate each front wheel in turn and inspect the constant velocity joint gaiters for splits or damage.
  • Also check that each driveshaft is straight and undamaged.
Step 17 Braking system
  • If possible without dismantling, check brake pad wear and disc condition. Ensure that the friction lining material has not worn excessively, and that the discs are not fractured, pitted, scored or badly worn.
  • Examine all the rigid brake pipes underneath the vehicle, and the flexible hose(s) at the rear. Look for corrosion, chafing or insecurity of the pipes, and for signs of bulging under pressure, chafing, splits or deterioration of the flexible hoses.
  • Look for signs of fluid leaks at the brake calipers or on the brake backplates. Repair or renew leaking components.
  • Slowly spin each wheel, while your assistant depresses and releases the footbrake. Ensure that each brake is operating and does not bind when the pedal is released.
  • Examine the handbrake mechanism, checking for frayed or broken cables, excessive corrosion, or wear or insecurity of the linkage. Check that the mechanism works on each relevant wheel, and releases fully, without binding.
  • It is not possible to test brake efficiency without special equipment, but a road test can be carried out later to check that the vehicle pulls up in a straight line.
Step 18 Fuel and exhaust systems
  • Inspect the fuel tank (including filler cap), fuel pipes, hoses and unions. All components must be secure and free from leaks.
  • Examine the exhaust system over its entire length, checking for any damaged, broken or missing mountings, security of the retaining clamps and rust or corrosion.
Step 19 Wheels and tyres
  • Examine the sidewalls and tread area of each tyre in turn. Check for cuts, tears, lumps, bulges, separation of the tread, and exposure of the ply or cord. Check that the tyre bead is correctly seated on the wheel rim, that the valve is sound and properly seated, and that the wheel is not distorted or damaged.
  • Check that the tyres are of the correct size for the vehicle, that they are of the same size and type on each axle, and that the pressures are correct.
  • Check the tyre tread depth. The legal minimum at the time of writing is 1.6 mm over at least three-quarters of the tread width. Abnormal wear may indicate incorrect front wheel alignment.
Step 20 Body corrosion
  • Check the condition of the entire vehicle structure for signs of corrosion in load-bearing areas. (these include chassis box sections, side sills, cross-members, pillars, and all suspension, steering, braking system and seat belt mountings and anchorage) Any corrosion which has seriously reduced the thickness of a load-bearing area is likely to cause the vehicle to fail. In this case professional repairs are likely to be needed.
  • Damage or corrosion which causes sharp or otherwise dangerous edges to be exposed will also cause the vehicle to fail.
Step 21 Petrol models
  • Have the engine at normal operating temperature, and make sure that it is in good tune (ignition system in good order, air filter element clean, etc).
  • Before any measurements are carried out, raise the engine speed to around 2500 rpm, and hold it at this speed for 20 seconds. Allow the engine speed to return to idle, and watch for smoke emissions from the exhaust tailpipe. If the idle speed is obviously much too high, or if dense blue or clearly-visible black smoke comes from the tailpipe for more than 5 seconds, the vehicle will fail. As a rule of thumb, blue smoke signifies oil being burnt (engine wear) while black smoke signifies unburnt fuel (dirty air cleaner element, or other carburettor or fuel system fault).
  • An exhaust gas analyser capable of measuring carbon monoxide (CO) and hydrocarbons (HC) is now needed. If such an instrument cannot be hired or borrowed, a local garage may agree to perform the check for a small fee.
  • The permitted emission levels in the following paragraphs vary according to the age of the vehicle. If a vehicle has been fitted with an engine taken from an older vehicle, it only has to meet the emission levels applicable to the older vehicle. It will be necessary to provide the MoT tester with satisfactory proof of the age of the donor vehicle (for instance, a registration document showing the engine number).
Step 22 CO emissions (mixture)
  • At the time of writing, for vehicles first used between 1st August 1975 and 31st July 1986 (P to C registration), the CO level must not exceed4.5% by volume. For vehicles first used between 1st August 1986 and 31st July 1992 (D to J registration), the CO level must not exceed 3.5% by volume. Vehicles first used after 1st August 1992 (K registration) must conform to the manufacturer's specification. The MOT tester has access to a DOT database or emissions handbook, which lists the CO and HC limits for each make and model of vehicle.The CO level is measured with the engine at idle speed, and at "fast idle". The following limits are given as a general guide: At idle speed - CO level no more than 0.5% At "fast idle" (2500 to 3000 rpm) - CO level no more than 0.3% (minimum oil temperature 60ºC) If the CO level cannot be reduced far enough to pass the test (and the fuel and ignition systems are otherwise in good condition) then the carburettor is badly worn, or there is some problem in the fuel injection system or catalytic converter (as applicable).
Step 23 HC emissions
  • With the CO within limits, HC emissions for vehicles first used between 1st August 1975 and 31st July 1992 (P to J registration) must not exceed 1200 ppm. Vehicles first used after 1st August 1992 (K registration) must conform to the manufacturer's specification. The MOT tester has access to a DOT database or emissions handbook, which lists the CO and HC limits for each make and model of vehicle.The HC level is measured with the engine at "fast idle". The following is given as a general guide: At "fast idle" (2500 to 3000 rpm) - HC level no more than 200 ppm (minimum oil temperature 60ºC)
  • Excessive HC emissions are caused by incomplete combustion, the causes of which can include oil being burnt, mechanical wear and ignition/fuel system malfunction.
Step 24 Diesel models
  • The only emission test applicable to Diesel engines is the measuring of exhaust smoke density. The test involves accelerating the engine several times to its maximum unloaded speed. Note: it is of the utmost importance that the engine timing belt is in good condition before the testis carried out.
  • The limits for Diesel engine exhaust smoke, introduced in September 1995 are:Vehicles first used before 1st August 1979: Exempt from metered smoke testing, but must not emit "dense blue or clearly visible black smoke for a period of more than5 seconds at idle" or "dense blue or clearly visible black smoke during acceleration which would obscure the view of other road users".Non-turbocharged vehicles first used after 1st August 1979: 2.5m-1Turbocharged vehicles first used after 1st August 1979: 3.0m-1
  • Excessive smoke can be caused by a dirty air cleaner element. Otherwise, professional advice may be needed to find the cause.
Changes for 2012

From January 2012 the additional items listed below (when fitted) are included in the test. At the time of writing (August 2012) they do not constitute reasons for failure, but they will be mentioned by the tester in an advisory note. It is intended that they become mandatory in due course, on a date yet to be advised. For up to date details consult the Vehicle & Operator Services Agency website or their Car MOT page.

  • Headlamp levelling and cleaning devices for HID or LED headlamps
  • Main beam warning light
  • Battery condition (no leaks) and security
  • Electrical wiring connectors security and damage
  • Trailer electrical socket security and damage
  • Trailer electrical socket operation (13-pin only)
  • Operation of the steering lock
  • Electronic power steering malfunction warning light
  • Electronic parking brake operation and warning lamp
  • Electronic stability control components and warning lamp
  • Brake fluid warning lamp illuminated or not working
  • Tyre pressure monitoring system (only on vehicles first registered after 1st Jan 2012)
  • Airbags, seat belt pre-tensioners and seat belt load limiters
  • Speedometer must be fitted and working
  • Indirect vision devices (radar, CCTV) - only when they replace obligatory mirrors

  • Note for visitors from outside the UK: the MoT test is performed annually on all vehicles 3 years old or more. Most countries have something similar, but the details will vary.