The 10 top reasons that HGVs fail their annual tests

The 10 top reasons that HGVs fail their annual tests

An EU directive revised the HGV MOT rules in 2014, slightly extending the range of vehicles obliged to have HGV examinations (lighter trailers, fast tractors), and changing some of the tests. The declared intention is to reduce the number of fatalities on Europe’s roads due to vehicle faults, from over 5 every day to zero. Both to protect your HGV drivers and other road users and to avoid expensive and inconvenient MOT fails, the following are issues to give thought to, as the MOT gets closer.

Headlamp beams

Beams are the single most common cause of fails. The new rules widen the tolerance for beam direction and simplify the test for light bleeding into the “dazzle zone”, but it should still be a priority check before the test.


The larger your vehicle, the more lamps it could have – side markers, fog lamps, registration plate lights, fork-lift lights and so on. It isn’t difficult to check they all work and are securely mounted. They must be the right colour, brightly lit, properly hooded (if they’re meant to be) and positioned correctly.

General braking systems

This is the reason for a fail in approximately 3.3% of tests. We hope you inspect your braking system regularly anyway, whether you’re the usual driver of your vehicle or not. That way you’ll know whether anything could cause a problem before the inspection becomes due.

Service brakes

2.5% of fails are from service brake tests. The kinds of test varies with the kind of brakes – air pressure, vacuums, hydraulics and so forth. A simple thing to check is that any hydraulic fluid isn’t simply too old to do its job.


Stiffness, looseness or sticky movement could get you a fail. Other than ensuring you have no loose bolts or brackets, there isn’t a lot you can do at the last minute, so try to be aware of developing issues well in advance of the test.


This is not easy to fix cheaply if you anticipate an issue, but why not do it in advance and save the extra costs of a MOT fail and unplanned off-road time? Keep your eye on the service history, so that you have an idea when bearings and other parts are approaching the limit of their expected mileage.

Parking brakes

The MOT test will check that the parking brake is working correctly when applied fully, with no unexpected looseness or movement.

Secondary brakes

The tests for secondary brakes are similar to those for parking brakes. Again, HGV drivers should report any change in braking behaviour promptly, so that it can be rectified.

Tachographs and speedos

Seals will be checked for tampering, of course, but a common cause of a fail is simply a time clock that no longer works properly. This is a common fault, so you might want to take a look before you put the vehicle into the test centre.


Routeing of wiring around the engine is a simple but common cause of a fail. It must be positioned securely so that it’s at no risk of either heat or mechanical chafing. The DVSA itself says that simple, regular upkeep would save almost half of vehicles from a MOT failure.
0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published.