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.

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

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.

Book a car diagnostic

For a limited time, get £50 off repairs over £150 when you book a diagnostic test. Offer ends 09/12/25, 09:00.^**
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.

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.

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

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

Reliance Auto Test Bicester

4.3/5

Reliance Auto Test has been in business for many years, branching out to our Bicester branch providing a one stop shop for all your Car & Van requirements. We have served local residents of Bicester and surrounding areas with a friendly, high quality service that has kept us in business. All our staff are fully qualified vehicle technicians and we are fully insured. Many of our customers come back year after year enjoying a service that is personal and great value. We are open for business 5 days a week, Monday to Thursday 8.00am - 6 pm, Friday 8.00am - 5pm and Saturdays By appointment only “Honesty is our best policy.

Unit 16, Wedgewood Road, Bicester, OX26 4UL

Darlington Mot Centre

4.9/5

Darlington Mot Centre Mot cars, vans , motor homes , motorbikes , trikes ,quads • Comfortable reception to wait in • Motorcycle class 1 and 2 only £25 • Class 4 cars and vans only £45 • Class 7 & motor homes up to 3.5ton only £50 • MOT's carried out up to 28 days before expiry - keep your original expiry date • Post card reminder service so you never forget your MOT again • Free re-test within 10 working days • No charge for head light adjustments We service and repair all makes of vehicles All makes serviced and repaired • Full and Interim service • Body shop repairs for those little scrapes, dings and re-sprays • Air-con new and old gasses repairs • Timing belts and engine repairs • Brake disks and pads • Exhaust and suspension • Tracking 4 wheel alignment • Tyres new and part worn • Batteries, starters and alternators • Diagnostics and engine management systems • Clutches and gear boxes

Darlington Mot Centre, 410 Whessoe Road, Darlington, DL3 0RP

Hardacres Garage.

4.9/5

Hardacres Garage is a family owned and operated business in the heart of Mid Devon serving the local community of Tiverton and the surrounding area. We pride ourselves in being open and honest. Our work is carried out by qualified mechanics who specialise in BMW, Land Rover and Isuzu's. All types of work is carried out including fabrication and welding, servicing and repairs of all makes of Cars Vans and 4x4s.

29-31 Leat Street, Tiverton, EX165LG

Portside Cars LTD

4.0/5

We are a family run business and it is important to us that your trust us and feel comfortable with us. We pride ourselves on giving the best and honest service that we possibly can with the quickest turnaround time.

Unit 8, Canal Bridge Enterprise Centre, Meadow Lane, Ellesmere Port, CH654EH

Magic Motors

4.7/5

Magic Motors are a car Servicing and repair centres which is open to both the motor trade and general public. If you own a used car dealership, lease company, have a fleet of company cars or you just love your car. Our guys and girls at Magic Motors can assist in preparation of your car to the highest standards. From smart repairs to vehicle mechanical repairs we have it covered. As a family owned business we have strong customer values where all our staff work to high standard. We can even take your car and prepare it for sale and then find it a new loving home. Using trade buyers, vehicle auctions and handling sales from our premises in Poole, you are promised a quick smart solution to the preparation and if needed the disposal of your vehicle. We work with local motor traders, lease companies and auction houses on a daily business in assisting them to get the best prices for their cars and looking the best. Give us a call with your requirements or direct message on our Facebook page https://www.facebook.com/MagicMotorsandMotorsports At Eurorepar Car Service, we’re all about keeping you and your car moving with confidence. As a trusted network of local garages, we provide high-quality car maintenance and repairs tailored to your needs – all at competitive prices. With our exclusive Brakes for Life program and a 2-year parts and labour warranty, you can drive away knowing you’re covered for the long haul.* Ask your Eurorepar Car Service Centre to fit Eurorepar branded parts to qualify. Claims under the 2-year parts and labour warranty must be made at a Eurorepar Car Service Centre. Discover expert care, unbeatable value, and peace of mind – all under one roof. Ready to experience the Eurorepar difference? Request a quote or give us a call today! *Terms and conditions apply.

Unit 3-4 Virage Business Park, 132-134 Stanley Green Road, Poole, BH153AP

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.