What is a car diagnostic test?

Car maintenance requires both personal and professional work, carried out throughout the year.

Sometimes there is a need to use specialised tools. Here, we discuss the importance of a car diagnostic test.

A car diagnostic is a process that involves using specialised tools and software to check the various systems and components in a vehicle for any issues or error codes.

Mechanics, and sometimes experienced car owners, can perform diagnostics to identify and sort any problems without needing to disassemble the vehicle.

This process primarily relies on the car's onboard computer system (ECU), which constantly monitors various functions and stores error codes when something goes wrong.

Most modern cars are equipped with an onboard diagnostics system that constantly collects data from sensors throughout the car. This error code can be read by the diagnostic tool.

The codes can give an overview of issues with the engine, emissions, fuel system, transmission, and other systems.

Drivers should look out for their engine management light, as this could indicate an error code.

In summary, using a diagnostic tool helps identify potential issues quickly, saving time and potentially money.

• What is a car service? Car service checklist
• Engine codes – what are they and how should you react to them?
• Car dashboard warning lights and symbols

A car diagnostic check typically includes a thorough examination of the vehicle's electronic and mechanical systems using a diagnostic tool.

The mechanic will connect a scanner to the car’s diagnostic port to retrieve error codes stored by the vehicle's computer system. Each code corresponds to a specific issue or system that needs attention.

Following this, the mechanic will then carry out the necessary fixes and maintenance and let the car owner know the relevant costs.

Once issues are identified and fixed, the mechanic may clear the error codes from the system, ensuring no further issues remain and that the vehicle's computer will continue monitoring normally.

With the RAC, drivers can expect to pay £99 when you book with one of our mobile mechanics.

Our mobile mechanics will spend up to 30 minutes checking your car for faults and talk you through any repairs you might need and give you a report for your records.

There are numerous ways we can check for faults, which could include plugging in to check your car’s onboard engine management system.

Our mechanics use parts from the manufacturer and provide a great service.

Car owners can expect to wait up to 90 minutes while a mechanic carries out a car diagnostic test.

However, the overall time spent at the garage may take longer if any work needs to be conducted by the mechanic.

These are the car diagnostic does to look out for, as they notify where the potential issue may be in the vehicle:

• B – Body. This includes issues with the air con, infotainment, airbags, and driver assistance.
• C – Chassis. This also includes steering, brakes, and suspension system.
• P – Powertrain. This refers to the transmission and various engine components.
• U – wiring and sensors. This error code is linked to the wiring and sensors across the vehicle and covers other unique issues with the vehicle.

There are over 200 fault codes, so having an experience mechanic is vital, so they can make the necessary fixes or adjustments.