What is a Vehicle Diagnostic Test? A Comprehensive Guide by M&BM Motors, Grays
Addressing issues early often reduces repair costs

At M&BM Motors here in Grays, Essex, we understand that your vehicle is more than just a mode of transport – it’s part of your daily life.
Whether it’s commuting to work, the school run, or those long weekend drives, keeping your vehicle running smoothly is essential.
One of the most effective ways to ensure your car stays in top condition is through regular vehicle diagnostic tests.
But what exactly is a vehicle diagnostic test, and why is it important? Let’s break it down.
What is a Vehicle Diagnostic Test?
In simple terms, a vehicle diagnostic test is like a health check-up for your car.
Modern vehicles come equipped with sophisticated onboard computer systems that monitor and control various components, from the engine to the braking system and even exhaust emissions.
A diagnostic test involves connecting your vehicle to a specialised scanner that communicates with the car’s onboard computer.
This scanner reads fault codes (known as Diagnostic Trouble Codes or DTCs) and pinpoints any issues that may be affecting performance or safety.
What Does a Diagnostic Test Check?
Here at M&BM Motors, when we carry out a diagnostic check, we look at several key areas, including:
- Engine performance issues
- Transmission faults
- Exhaust system problems
- Brake system warnings
- Airbag and safety restraint systems
- Emission levels
- Battery and charging system health
If you’ve noticed a warning light on your dashboard – whether it’s the engine management light, ABS light, or any other indicator – a diagnostic test is the fastest and most reliable way to identify the root cause.

Why Are Vehicle Diagnostics Important?
Many car problems start small but, if left unchecked, can develop into major repairs. By catching issues early with a diagnostic test, you can avoid costly breakdowns and keep your vehicle safe and roadworthy.
Some key benefits include:
- Early Detection of Problems: Early detection can prevent minor faults from turning into major costly repairs.
- Save Money: Addressing issues early often reduces repair costs.
- Improve Safety: Faulty brakes or steering components are dangerous. Diagnostics help spot these problems early.
- Better Fuel Efficiency: Problems like faulty sensors can cause poor fuel consumption.
How Long Does a Diagnostic Test Take?
In most cases, a diagnostic check at M&BM Motors takes around 30 minutes to an hour. If the test reveals any faults, our experienced technicians will explain the findings in plain English – no confusing jargon – and discuss the best way to fix the problem.
Do I Need a Diagnostic Test If My Car Feels Fine?
Even if your vehicle seems to be running smoothly, modern cars can store hidden fault codes that don’t trigger a warning light immediately. Regular diagnostic checks are especially recommended if:
- Your car is due for a service
- You’re preparing for a long journey
- You’ve recently bought a used vehicle
- You want peace of mind
Why Choose M&BM Motors for Diagnostics in Grays?
At M&BM Motors, we’ve built a reputation across Grays and the wider Essex area for honest, transparent service and high-quality workmanship.
Our technicians use the latest diagnostic tools compatible with all major makes and models, ensuring accurate results every time.
We pride ourselves on offering clear advice and no-obligation quotes. If your vehicle does need repair work following a diagnostic test, you’re in safe hands with our experienced team.
Book Your Vehicle Diagnostic Test Today
If you’re experiencing issues with your vehicle or simply want to ensure everything is running as it should, contact M&BM Motors today. You can book a diagnostic check by calling us on 01375 399955.
