Van VTN DOE Test Preparing Guide

Guide to preparing for your VTN/DOE

The Vehicle Testing Network (VTN) test is a structured test where the testers follow a set routine, and use specific equipment to test the road-worthiness of a vehicle. As a result of the test, the tester determines the current working condition of the vehicle and either issues a pass certificate or advises a retest and the maintenance/repairs required.

While you may not be a mechanic or have much experience with the mechanical workings of commercial vehicles, there are a number of things that you can do before the test to prepare your vehicle to hopefully pass. Doing some simple things yourself can mean your vehicle passes the test and does not fail on something simple that you could have rectified yourself before going for the test. This test is sometimes known as the Commercial Vehicle Test (CVT).

We have come up with a quick guide for you which will hopefully help you to prepare your vehicle for the test. Following this guide cannot guarantee that your vehicle will pass but it will help to increase your chances of getting a pass certificate.

Engine and Coolant Levels

If you drive a van you should be familiar with the location of the oil and coolant indicators on your vehicle. If not this is something that you should look into. These can be very important things to know about for a van driver.

Vehicles often get tested with very low levels of oil or coolant, which is a problem for the tester as he needs to smoke test the vehicle. This is done to measure the Co2 emissions of the vehicle and tells the tester how efficiently the engine runs. If a vehicle is very low on oil, there is a risk of the engine getting damaged during the test. In most cases if the tester sees that there is a low level of oil in the engine they will not perform the smoke test, resulting in a fail.

Tips for Checking the Oil

  • Warm up your engine and turn it off.
  • Remove the dipstick and clean it with a cloth.
  • Check your oil level and top up if needed with the correct grade of oil.
  • The oil type can be found in the user manual or an internet search.

Coolant levels are just as important for the same reasons outlined above, checking coolant can sometimes be a little trickier than the oil, depending on vehicle type. Smaller vans and jeeps typically have an expansion tank in the engine bay. Usually these tanks are translucent with max and min markers. This means you can quickly tell if your coolant levels are high enough. With larger vans the expansion tank can be harder to read, they may only have a window and float to show you the level of fluid. It also makes sense to check the level in the radiator, there is usually a cap on the radiator or close-by that you can check.

PLEASE NOTE: Perform all coolant checks on a cold engine to avoid injury.

Lighting and Electrical

Another common occurrence when presented for test are vehicles with lights that are not functioning. This can be a simple fix for you before the test. It’s best to get a friend to help you check all are functioning correctly. There are 2 main causes of lights not working,

  • Firstly, bulbs themselves are prone to failure but easily replaced.
  • Secondly, blown fuses. Most vehicles have a number of spare fuses located in the main fuse box of the vehicle. Your vehicle manual will show you the location of the fuse box and the relevant fuse for the light that is not functioning.


The DOE test involves a check of tyre condition. Tyre threads should be above legal limit 1.6mm in depth and evenly worn. Uneven wear is a problem that occurs on many vans. Cornering and loads can often cause excess thread wear on the extremities of the tyre. A pro-active way of dealing with this is to get your tyres positions rotated on a regular basis. This involves swapping the tyres from the front to the rear. When getting your vehicle serviced you should ask your garage to perform this for you.

Tyre condition involves checking the side walls for impact damage and bulges. Weathering of tyres can occur if they are quite old. Cracks and sidewall damage are the major causes of tyre blow outs.

Prior to bringing your vehicle in for inspection you can check the tyres for wear and inspect the side-walls yourself and replace if need be. This is also a good time to check your tyre pressure. Tyre pressure recommendations are usually on the tyre themselves but you can also check driver’s door frame on the vehicle. Normally there will be a sticker with the manufacturer recommendation of tyre index and operating pressure.

Keeping your tyre pressures in this range can:

  • Reduce uneven tyre wear.
  • Improve the handling of the vehicle.
  • Improve the braking performance and predictability.

Braking and Suspension

This can a difficult area for you to examine yourself without specialised equipment. A major component of the DOE test is the braking performance of the vehicle. The braking performance is measured on the vehicle under a load simulation, the purpose of this is to check how efficient the braking is when stopping a vehicle with a load. The handbrake performance is also checked as part of this. Generally if the brakes on a vehicle are sub-par, you will be aware of it. You can usually examine the condition of the brake disc and pads with the aid of a flash-light. If the brake discs have grooves on the surface, this can indicate that they are no longer usable and that they, and the brake pads, may need to be replaced.

On the suspension side of things, the vehicles are checked for component wear. Kingpins, ball joints and bushes are visually inspected and then tested on hydraulic plates to simulate movement under load. If you think your vehicle suspension feels tired, it is usually an indication of worn out components. Again this is something that is difficult for the average user to check, and as such you should get a qualified mechanic to check this for you.

Once your van passes the VTN the next thing to have is tax and Insurance. When your van passes the VTN give our team a call and we will be more than happy to give you a great quote on your van insurance. You can call us on 01 660 6900 or you can fill out our van insurance quote form online.

As well as providing Van Insurance, we also provide great rates and cover for Fleet InsuranceHaulage Insurance and Public Liability Insurance.