FAQs: What happens during an Engine Diagnostics?

Have you ever found yourself in the situation where you’re driving along and all of a sudden the warning light pops up on your dashboard and you don’t have a clue why? Something must be wrong but you have no idea what and it throws you into complete panic mode?

Engine Diagnostics

Well, you’re probably not the only one, but the most important thing is to know what to do and how to handle the situation. Professional mechanics can carry out a thorough diagnostic procedure, using the latest tools and technology in the industry to investigate the issues that could have caused the warning light to come on.  Carrying out an engine diagnostic will allow the mechanic to collect data and repair the vehicle wherever necessary, identifying why the engine may not be functioning properly and repairing the damage.

Generally speaking, an engine diagnostic machine is plugged into the car’s computer. The computer returns a diagnostic code that can be used as a reference against a list of codes from the manufacturer. For instance, if the engine is in fine working order, then the device will say so or, alternatively, if there is a problem, a code (or several) will be displayed.

Codes can mean a whole host of things, and it is the mechanics job to determine what could be causing the code to be flagged up on the device, giving the vehicle owner some sort of idea about what it will cost to rectify.

A thorough engine diagnostic will include:

  • Retrieving data

An on-board computer system is used to locate computer codes, freeze-frame data, software version numbers and critical sensor data and status information in order to make an accurate diagnosis of the vehicle.

  • Verification testing

This determines whether the system properly meets the specification. The tests at this stage include engine vacuum and back pressure, ignition and fuel system and emissions system. A failure in these systems can cause the warning light to appear, although it could be falsely highlighting a problem with a circuit or component that could lead to unnecessary replacements of certain parts.

  • Pinpoint testing

It is a manufacturer requirement to pinpoint test the circuit or component in order to make a well-informed diagnosis. This process includes wiring diagrams, electrical and mechanical tests, bi-directional control tests and visual inspections.

  • Service bulletins

Utilising service bulletins helps find out whether the problem has been a recurring issue that is known for a particular vehicle type. There is still the need for testing, as certain systems cannot have a service bulletin performed on them.

  • Car repair

This includes replacing parts, cleaning components, carrying out manufacturer’s technical updates, making updates to the vehicle’s software and wiring repair or replacement.

  • Verify repair

After all the necessary work has been completed, the vehicle needs to be re-tested.

So, next time the warning light shows up, remember to get your car booked in to your local car garage as soon as possible and let the experts sort the problem out for you!


Engine diagnostics can make the repair process for your vehicle go much smoother, helping the mechanic get to the root of the problem faster. So if you’re looking for a reliable company in Lincoln to perform engine diagnostics on your car, then please get in touch with Auto Exhausts and Tyres. Our team have expert knowledge and all the necessary equipment to carry out effective engine diagnostics on all vehicles – simply get in touch with us to find out more or to book an appointment.