Macias Diagnostics, LLC. ASE Master Certified(L1), ASE A9 Diesel Certified.

Light Duty Diesel Repair in Cumming, GA.
Opening at 9:00 AM on Monday
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Working with our local Tree Service Companies getting them ready to head for Hurricane Relief!!
We appreciate your business. Be safe 😇

We will be closed on Monday, May 27th in observance of Memorial Day. We appreciate your business and will see you on Tuesday, May 28th. Have a happy and safe holiday.

We service RV's here at Macias Diagnostics! Call us for an appointment for your summer service. We will get you ready for your summer trips.

Mobile RV Service in North Atlanta Area. Class A Diesel Pushers, and Class ABC gas engines.

* Oil Changes
* Generator Service
* Fuel Filter
* Battery Replacement

Call us today for an appointment!



4 months ago
Very nice professional and helpful
- Aaron S
2 years ago
I went Macias Diagnostic because I had an issue with a check engine light on my vehicle and at times it wouldn't start. I was greeted by Mark. He was friendly and welcoming even though I didn't have an appointment. I could tell he was busy but he checked out my vehicle anyway. He took his time and explained to me what was going on in terms I could understand. I left my vehicle with him and was able to pick it up the next day. Other establishments (which will remain nameless) told me my problem was bigger than it was. They tried to charge me an obscene amount of money. Mark at Macias was honest and didn't take advantage of me. I will definitely go back to Macias! Thank you Mark!!!!
- Brandy A
a year ago
I had blown my water pump on the way back from a job in SC, googled repair shops in Cumming and called Macias. I told Mark the issue, he was very friendly and honest with letting me know about what it would cost to replace it. When he got into the engine, he found part of the serpentine belt had split away causing it to destroy my fan clutch and taking out the fan clutch wiring harness. He called me right away to inform me of the issue and the new price to get my truck back on the road. I asked him to save me the damaged parts he would replace and he had no issue with doing so. My truck was ready when promised and damaged parts waiting for me. Excellent work and people to do business with. I found my new repair shop!!!!!
- Tony C

Diesel Specialist, Current Training

 Personable technical service and support.

Contact Us


Call now
  • (470) 695-5920


Get directions
5730-A Chattahoochee Industrial Park
Cumming, GA 30041
United States

Business Hours

Mon:9:00 AM – 6:00 PM
Tue:9:00 AM – 6:00 PM
Wed:9:00 AM – 6:00 PM
Thu:9:00 AM – 6:00 PM
Fri:9:00 AM – 6:00 PM
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