Compare prices on car diagnostic check and fault finding

4.5 (25)
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Prices on car diagnostics and fault finding

The average prices and savings for the car brands shown are based on different models and years. You must therefore create a job and compare quotes to see your actual price and savings.
Make Compare and save* You save on average* Ratings
Ford £41 43%
4.7 (3)
Mercedes-Benz £52 48%
4.7 (3)
Mini £59 45%
Peugeot £43 42%
5.0 (2)
Vauxhall £63 55%
5.0 (2)
Volkswagen £46 45%
5.0 (1)

Ratings of car diagnostics

Junction 59 Classics Ltd
2 months
The. Service I received was very friendly and professional. The price was reasonable and everythi...
Michelle Q.
Ford Fiesta (2018)
RSH Performance LTD
3 months
Richard was very helpful, the service was quick and friendly. I am definitely using this garage a...
Helena H.
Ford Focus (2011)
D&G Auto Car Repair
3 months
Service and quality of work, would definitely recommend😊👍
Clare S.
Ford EcoSport (2019)

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Compare quotes on: Car diagnostic and fault finding

Choose garages with fault seeking tools


Diagnosis on the car can be one of the most time-consuming jobs.

Often, the mechanic will say that when “this gadget displays an error”, there may be 5-10 other components that may be the cause of it.

Nowadays, most cars are controlled by a computer which can be monitored, upgraded and controlled if you have the right tool for it.

The garage uses diagnostic tools

The mechanic's work is now often based on being able to interpret data from a computer that is connected to the car. Most garages have a diagnostic tool which they can connect to the car's computer, and thereby get a lot of information. At the same time, they can adapt the options, but they must know what they are doing! That is why most mechanics go through continuous training for technical equipment.

The most important diagnostic tool is that sensors can measure errors in the system. That way the mechanic finds it easier to locate the defective parts and replace them.

You can buy an adapter for £20, which you can connect between your computer and your car, but who would dare to even tinker with the settings? Only garages that have the right equipment and mechanics with the proper training can perform proper troubleshooting and fault code reading on your car.

You can always be confident about the quality of the work carried out, because only affiliates with quality garages, which are subject to ongoing evaluation and are rated by car owners.

Diagnostics at the garage

During a diagnostic, all parameters are checked that appear in the diagnostic tool. Both Electromechanical and electrical equipment are looked over. The mechanic has his experience, but also repair manuals, information on the computer and can draw upon the knowledge and expertise of his or her colleagues.

Sometimes it's easy to find a fault with the diagnostic tool, while other times it can be a time consuming task. It can be a loose cable, showing an error in a completely different area than where the loose connection is actually located.

It's in your interest, when you book a job at that you get a fixed price for the task. But if the task turns out to be quite different, or more errors appear, the garage will contact you before doing anything. The fixed price covers what is agreed, not what else is discovered during the repair.

If an error is hard to describe, you need to pay extra attention to the quotes you get. It is not certain that the cheapest quote remains so, when the car is at the garage. Read the description in the quotes you receive carefully and consider which one of the descriptions makes you trust that the garage is aware that the error might be time consuming to diagnose.

You can also look at the reviews other car owners have given the garages and assess who you trust to do the work.

Typical errors and defective parts

There are so many parts that may be defective and cause errors in the instruments or in the diagnostics tool. Some of the errors are pretty obvious, and you'll probably be able to fix them yourself. Other errors are less visible, and require some insight into how the car is put together.

Here is just a small sample, so you have an idea of what you might need in your description of the issues for the garage:


If something stops working, such as window wipers, heat or radio, it may very well be a blown fuse. You can look in the manual and see which fuse has caused your vehicle to become defective, and then remove the fuse box cover to check the fuse. If you do not know where the fuses are located, it is also in the manual.

Auto bulbs:

Most new cars have a service light that lights up if there is a bulb that is defective. Then you just need to figure out in which light to replace the bulb. Some might think it is easy to change a bulb and can therefore do it themselves, however on some vehicles, bulbs are hidden behind the cars interior and can be tricky. This is more likely to be at the rear of the vehicle. In this case, it’s good to have a friendly mechanic to help, and this will cost very little.

More and more cars have built-in navigation systems. If it stops working, it is not easy to get to, unless it is a detachable unit. It's limited what you can do, other than to restart it. If it is a detached unit, it will often be possible to connect it to a computer, and thus update or restart it.


Cars need power to start, but also to drive. It is the generator that provides charge to the battery and gives power to all the electrical components and gadgets. If the generator is faulty, it does not supply power to the car, because it does not charge the battery as you drive, and therefore you will only go as far as your battery allows you. When the battery runs down the car comes to a halt.


Engine rpm is needed to start the car. In the old days where a hand crank was used, it is now a starter. If it does not work, you can push petrol cars to start, but not diesel cars. The trick here is to put the car into 2nd gear, release the handbrake and get someone to push the car, while the clutch is pressed all the way down. Release the clutch slowly while you turn the key to start. The car should now start.

Spark plugs:

If the car is misfiring, it may be the spark plugs. If you are not afraid to get your hands dirty, you can find a special key to pull the spark plugs out with, and try to clean them. If necessary, use a piece of fine sandpaper between the two contact points. If they are very dirty and worn, you can change them. On the other hand, it is one of the things a garage can fix easily for you, and checks when the car is serviced.

Ignition coil (petrol):

The ignition coil will deliver the power that causes the spark plugs to make a spark that ignites the fuel in the cylinders. The ignition coil sends power to the carburetor that controls the ignition.


Older petrol cars! Wires lead up from the spark plugs and ignition coil to the carburetor. It is important that the cables from the spark plugs sit in the correct order, otherwise there can be sparks at the wrong time. If you are unlucky, the engine can be damaged, so most cars only have cables in the necessary length. Connect the shortest first, and then the longest. A typical error may be a leak, so moisture gets in the carburetor. This will "short-circuit the carburetor" and does not provide power to the spark plugs. Here oil might help, by having a moisture displacing effect.

Electronic fuel injection:

In practically all new petrol cars, electronic injection of fuel is used, instead of the traditional carburetor.

Airconditioning and climate control:

You can check that the cables and connections are tight and that there is no dirt but that's about it. Upon failure of airconditioning and climate control you need to contact a garage. Chemicals are used in the system and it is both expensive and harmful to the environment if not treated properly.

Oil spills:

If you see spilled oil, there are many parts that can be the cause. Look where the oil is located on the ground, and see if you can find the leak from above the engine compartment. You may need to look from below, but it is a little tricky. If you cannot see where the oil comes from, you can at least take a picture to document where the oil is approximately dripping down on the ground. It can give the garage an idea of what may be leaking. When you create a job, you can attach the picture.


If the lights concerning safety systems such as ABS, airbag or other equipment turns on, you should get a garage to look at it. It’s not worth taking chances. It may also be the electronic immobilizer, the BAS, lane-change alarm, tire pressure monitoring, or one of the other security measures that have been invented, and they all of course have some detectors or sensors that can be transmitted to show an error. In the manual, you can see what the different lights mean.

Garages with fault seeking and diagnostic tools can make finding problems with your car’s engine or electrical work faster and easier. All new Ford, Vauxhall, Volkswagen, Peugeot, Renault, Kia, Nissan and BMW cars are controlled by a central computer. This computer monitors the car’s performance and identifies issues as they arise. Tapping into this computer with fault seeking and diagnostic tools makes car maintenance and solving issues with noise, engine trouble or other problems, easier, faster, and cheaper. Check for the best prices of garages near you that offer fault seeking and diagnostic analysis of your vehicle today.

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Are you listening to your car?

When describing the fault you are experiencing with your car, it is important to describe it as accurately as possible. Otherwise it can be difficult to come up with an educated guess as to what is wrong and what it will cost. If there are visible signs that something is wrong, you can upload pictures in the job description to help the mechanic do a precise quote.

If it is a noise, you can describe this too. Often a defective part mean that the engine sound is mixed with other sounds, and if you can locate the murmur of the engine, the garage may know what is wrong.

If you need help with describing the error, you can call Autobutler and ask one of our in house mechanics for advice on free phone 0203 630 1415. You can also use our chat feature in the lower right corner of our website.

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