A diagnostic check can offer a valuable report on the condition of essential parts like the engine, transmission and exhaust.

Giving you the chance to detect problems early, booking a timely diagnostic test can save you the cost of expensive repairs in the long run.

Read on and find out what a car diagnostic test is, how much it costs and why you should book one.


What Is a Car Diagnostic Check?

A car diagnostic check is a process in which the vehicle’s engine control unit (ECU) uses sensors to identify issues as they occur.

These issues can generate a specific error code which will then be represented on the dashboard via the corresponding warning light.

Though the dashboard can highlight that there is a problem, specialist vehicle diagnostics equipment used by trained technicians is required to read the error code and understand the extent of the issue.

The test can report on the condition of various parts of your vehicle, including the following:

  • Engine
  • Transmission
  • Ignition coils
  • Exhaust
  • Fuel injectors
  • Oil tank
  • Airflow
  • Coolants
  • Throttle
  • Brakes

As such, a diagnostic test is an essential step in ensuring your vehicle’s safety and functionality.

If your car is showing signs of deterioration, a diagnostic test can point you in the direction of what needs to be fixed.


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How Much Is a Diagnostic Test?

In the UK, a car diagnostic test can cost anywhere from £30 to £100.


How Do Car Diagnostic Tests Work?

During a car diagnostic test, special software is used which can highlight developing faults that are causing problems with your engine or other systems.

These issues can be detected via built-in processors, sensors and microchips.

The engine control unit (ECU) in your vehicle is where your engine’s sensors can report anything out of the ordinary.

If there is a problem, the ECU will illuminate the relevant light on your dashboard.

When the sensor detects a fault, a code is stored in the car’s computer system.

The mechanic plugs their diagnostic tool into your ECU, allowing them to access the codes and determine which parts need to be repaired.

Once they have fixed the issue, they can clear the fault codes and your ECU will revert back to normal – where it will continue to scan for future issues.


What Can a Car Diagnostic Test Tell You?

A diagnostic test can tell you about a range of issues that your vehicle could be experiencing.

This can include problems such as low engine coolant levels, poor fuel injection system performance, too low or high RPM levels, ignition coil failure or bad ignition timing.

It can also tell you about problems with vital components such as the engine, transmission, exhaust and brakes.


Do I Need to Book a Car Diagnostics Check?

You may need to book a diagnostic check if you notice any of these warning signs:

  • An illuminated engine warning light
  • Strange sounds
  • Smoke or steam from bonnet
  • Vibrating or pulling under brake


How Long Does a Diagnostic Test Take?

A diagnostic test can take anywhere from an hour to 90 mins to complete.

The test can take longer if components need to be removed in order for the check to be carried out.


Is a Car Diagnostic Test Worth It?

The biggest benefits to booking a car diagnostics test are:

  • Early detection of problems
  • Improved fuel efficiency
  • Enhanced vehicle performance
  • Emission standards compliance

A diagnostic test can detect problems with your car even before you break down – helping you understand issues such as illuminated dashboard warning lights or unusual noises.

By being proactive and spotting potential issues quickly, you can save yourself money in the long run.


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