Car Diagnostics | Book a Car Diagnostic for your Mercedes

Trustpilot rating for all RAC Mobile Mechanics.

Why choose the RAC for a car diagnostic?

With RAC Mobile Mechanics, you can avoid the hassle of taking your vehicle to a garage. They can do a vehicle diagnostic check on your driveway, so you don't even need to leave the house.

When it comes to diagnosing issues with your vehicle, our friendly expert mechanics are here to help. We use state-of-the-art diagnostic equipment to accurately identify any problems, ensuring your vehicle runs smoothly and safely. The price includes the diagnostic service – no hidden costs. Just friendly, honest experts.

RAC Mobile Mechanics can carry out car diagnostics on popular Mercedes models such as A-Class, C-Class, GLC, E-Class, and EQA. This service is completed at your home or workplace, following Mercedes maintenance guidance and using OEM‑equivalent parts. You get clear pricing, real‑time updates and a convenient, no‑hassle experience.

Close up of an RAC Mobile Mechanic underneath a car

Our top pick for your Mercedes

We’ll come to you at home or work

RAC Mobile Mechanic for your Mercedes

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At the RAC, we’ve got over 125 years’ experience in offering complete peace of mind® to our members. We’re best known for our breakdown service. And now – our new RAC Mobile Mechanics are here to help make every day motoring easier. If you need a service or repair, they’ll come to you at your home or work.

Close up of an RAC Mobile Mechanic running a vehicle diagnostic check

Book a car diagnostic

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

OEM quality parts

We use original equipment manufacturer (OEM) standard parts, which means every new part will be the same standard and same quality as the original part it replaced.

Mechanics you can trust

Our mobile mechanics are friendly, honest, and backed by the RAC.

Book a repair

It’s easy to book a car repair online. We bring the garage to you with RAC Mobile Mechanics, or find a trusted local garage. Common repair jobs include:

Clutch Replacement

We diagnose and repair clutch issues – whether your clutch is heavy or slipping, or you’re having trouble changing gears.

Alternator repair

We check and correct alternator faults to keep your charging system running smoothly.

Oil change

Oil is vital to a healthy engine, so it’s important to change it regularly.

Brake pads & Discs

If your brakes are making noise or you’re noticing reduced stopping power, it’s likely time to replace your brake pads or discs.

And it’s not just car diagnostics that we do for your Mercedes

Mobile mechanics bring the garage to you, saving you the hassle of getting your car to a garage. If you need a service or repair, they’ll come to you at your home or work.

A close up of an RAC mobile mechanic looking under the hood of a car

Try one of our RAC Approved Garages

View all garages

Great Horkesley Garage

5.0/5

First established in 1994, we have decades worth of experience to tackle anything you challenge us with! We are a very successful, family run business that provides MOT, servicing, fuel sales and a shop for everyday essentials. Our mechanics are fully qualified and committed to providing a high quality service at reasonable prices on all makes and models of cars and vans.

The Causeway, Great Horkesley, CO64EJ

IN'n'OUT Autocentres Liverpool

4.2/5

At IN’n’OUT Autocentres we offer fixed prices MOTs and Servicing for any make and model of car with no hidden extras. We are proud to be a ‘Which? Trusted Trader’ so we are really a garage you can trust. We also have a 5 Star Trustpilot reviews rating. We provide OEM parts and 12 months warranty on all parts and servicing. We only use premium Castrol oils in all servicing. Our services are all completed ‘while-u-wait’ so you have never have the inconvenience of losing your car for the day. You can watch your car as it is being worked on through the viewing window or sit back and relax in our clean and comfortable customer lounges with FREE Wi-Fi and coffee and read the latest magazines. Check out our latest reviews and BOOK NOW!!

Speke Hall Road, Liverpool, L24 9HW

Fir Tree Autocentre (ub7)

4.0/5

As a reliable, local garage, we provide a range of car services for our customers. This includes MOT's, engine diagnostics, car servicing and car repairs at affordable prices. We work on providing low-cost repairs and services without affecting the quality of our work. As a result, we tailor our car services specifically to your vehicle and your driving needs. Our team take the time to talk each customer to make sure we can understand your needs and budgets in the hope that we can provide quality car services for every customer that walks through our door. All our mechanics who work for Fir Tree Autocentre in West Drayton are highly trained to the highest standard. This allows us to help worried car owners with any car problems they might be having. In addition to this, it allows us to work on any make or model of car and never have to turn a customer away. Keeping up to date with the latest tools and technology allows for more efficient and accurate repairs. In other words, we make sure our customers get their cars back on the road as soon as possible.

Unit 3-4 Horton Close, West Drayton, UB78EB

Road Two Automotive

4.5/5

Servicing Repairs Diagnostics Vehicle Tuning Clutches Exhausts MOT preparation Tyres

Unit 17 18 Cosgrove Business Park, Anderton, Northwich, CW96FY

A1 Motorist Centre

4.9/5

A1 Motorist Centre was first established in 2005 moving to our present site in late 2006. Our aim is to offer the latest technology that the motor industry can offer, combined with good old fashioned values and excellent customer care. We offer you a clean comfortable reception / waiting area with complimentary refreshments, free Wi-Fi internet connection and toilet facilities (this also includes disabled access). From here you will have a full view of the workshops so that you can watch as we work. We offer many services and our advice is free and impartial. We are members of the Good Garage Scheme and the Motor Industry Codes of Practice.

Unit 2, Patricia Way, Industrial Estate, Broadstairs, CT10 2LE

Frequently asked questions on car diagnostics

How much does it cost to diagnose a car problem?

The cost you pay can vary depending on the type of car and how complicated the diagnostic test. Check with your mechanic for a quote.

Is a car diagnostic test worth it?

Yes, a diagnostic test may save you a lot of money. It finds issues early before they become costly repairs. It can also keep your vehicle running efficiently and safely

Can I do a car diagnostic myself?

While you can buy a diagnostic tool, interpreting the results needs expertise. It’s best if you to have a professional mechanic perform the test.

How long does a car diagnostic test take?

Diagnostic tests take from 30 minutes to a few hours. This depends on what issues are being looked at.

What are common car diagnostic codes?

Common diagnostic trouble codes include:

P0300: Random/Multiple Cylinder Misfire Detected
P0420: Catalyst System Efficiency Below Threshold
P0171: System Too Lean (Bank 1)

These are general examples, so your car may have different codes. Always check with a mechanic so you get an accurate diagnosis.

Is a car diagnostic test necessary for a service?

Yes, they are. Regular diagnostics can help keep your car in good health. It makes sure that underlying issues are addressed quickly, so you can drive with peace of mind on the road.

Again, keep in mind that mechanics might have their own checklists. Chat with your mechanic to be sure that they address any specific issues you have.