Top 10: the most common reasons for HGV annual test failure

Some 417,767 HGV annual tests were undertaken in the 2015/16 financial year, with an initial failure rate of 17.2%. Commercialmotor.com looks at the top 10 reasons why trucks failed their test in 2015/16, according to the DVSA.

9/10. Wiring

Wiring issues accounted for 1% of the HGV fails recorded in 2015/16 – approximately 428. According to the DVSA’s HGV inspection manual, examiners will check the condition and security of the truck’s wiring during the annual test, making sure it’s positioned so that it is unlikely to be chafed or damaged by heat.

9/10. Speedometer/tachograph

Level with wiring in terms of frequency, speedometer and tachograph faults also accounted for 1% of the defects that contributed to annual test failure last year. Trucks must have a tachograph fitted unless the vehicle or operator is exempt from tachograph regulations, and tachograph seals will undergo a visual check. A truck will fail its test if, for example, the time clock is inoperative.

8. Parking brake performance

Some 1.2% of truck test fails involved an issue with the parking brake. An annual test will check if the mechanism is secure and is functioning correctly when fully applied.

7. Secondary brake performance

Secondary brake issues represented 1.4% of the issues discovered at annual tests last year. This is checked in the same way as the parking brake.

6. Suspension

According to the DVSA’s HGV inspection manual, examiners will check that a vehicle’s suspension is secure, is attached correctly, is in a good condition and free of defects. Suspension issues were responsible for some 1.6% of HGV annual test failures in 2015/16.

5. Steering mechanism

Steering mechanism issues accounted for 1.9% of annual test failures last year. Vehicle examiners will check that the mechanism functions correctly and is not too stiff or rough, according to the DVSA’s guide.

4. Service brake performance

Some 2.5% of truck test fails concerned service brake performance. Like with other brake checks, the method of inspection will vary depending on the type of braking system the truck has (air pressure/vacuum, hydraulic system, etc).

3. Brake systems and components

Issues with brake systems and components represented 3.3% of truck MoT failures in 2015/16. Examiners will check that the brake systems are not damaged and function as they should.

2. Lamps

Problems with HGV lamps represented some 3.8% of annual test failures last year. Examiners will check all lamps fitted to the vehicle, including headlamps, fog lamps, stop lamps, side marker lamps, rear registration plate lamps, and lamps fitted to vehicles with rear-mounted forklifts. The truck will fail its annual test if any lamps are missing or insecure; are not showing a light of the right colour, are incorrectly positioned; are not the correct colour or are too dim.

1. Headlamp aim

Headlamp aim continued to be the most common reason for truck MoT failure last year, representing 4.8% of annual test failures. In 2015 the DVSA changed the way it assessed headlamp aim on trucks and buses to provide a more consistent standard, which resulted in a significant reduction in the number of commercial vehicles failing this part of the test. The change involved an extension of the tolerance band for headlamp aim.

The DVSA has published a guide to help vehicles pass an annual test headlamp aim check.