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    Quantum Mobile Mechanic

    4.8 (169 reviews)
    Closed 9:00 am - 12:00 pm

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    Response time

    2 hours

    Response rate

    100%

    Services - Quantum Mobile Mechanic

    Auto engine repair

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    Recommended Reviews - Quantum Mobile Mechanic

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    He wanted me to waive my rights to a full refund. I had to pay another mechanic to fix what he was hired to do.
    Lori P.

    I hired this mechanic to replace the cinching actuator on my Tesla. Immediately after he completed the work, my car began making loud, abnormal noises that never existed before. My door handles started making a loud squeaking/horn-like sound. When I opened my trunk, it sounded like it was malfunctioning or "dying." The same noise occurred when the trunk closed. When I opened my doors, the noise came from the trunk again. Even when I backed into my driveway and pressed the brakes, my car made a loud honking sound. All of these issues began after his repair. I contacted him immediately to let him know something was clearly wrong. Instead of taking responsibility or offering to inspect the problem, he became defensive and accused me of lying. He claimed the issues were preexisting and said I had tampered with my own car. He talked over me, became argumentative, threatened to cut business ties, said he would block my number, and abruptly hung up on me. He also blamed me for "self-diagnosing," even though I was simply describing the symptoms I was experiencing--something any customer would do. I hired him because he is the mechanic. It is literally his job to assess, diagnose, and fix problems. Instead, he refused accountability and demanded I pay him an additional $250 just to run a diagnostic to determine whether he caused the problems. Every reputable mechanic I've worked with in the past has stood behind their work. This one did not. He then sent me a disclosure form he wanted me to sign stating that I would only receive a partial refund if he decided the issues were his fault. I did not agree to this. When I didn't respond to his repeated messages, he texted again saying that after "some thought," he would now be willing to refund only a "portion" of what I paid. I paid him $350. When I declined to pay the additional $250 diagnostic fee, he argued with me and repeatedly stated that because I said no, I was "accepting that this is the end of the issue," then hung up on me. To document the abnormal noises, I opened and closed the liftgate several times. During this process, a panel that concealed the wiring fell off its hinges. A Tesla-certified mechanic later told me this was because the panel had not been screwed in correctly. I ultimately had to hire a Tesla-certified mechanic to fix what was done. Based on the symptoms I described over the phone, he immediately recognized that the wiring had been done incorrectly. When he inspected the vehicle, he confirmed that multiple connectors were improperly rewired, including the liftgate being wired into the speaker system and the trunk light being wired incorrectly. The horn was sounding as a warning that something was wrong. This was not only careless -- it was a safety concern. This mechanic was rude, dismissive, unprofessional, and completely unwilling to stand behind his work. Based on my experience, I would strongly caution Tesla owners and anyone with a modern vehicle against using his services. *** This is in response to Jane's response. PLEASE READ as this is very important. James claims he offered a "warranty check," AKA "diagnostic," but only if I paid him an additional $250 for his time. I declined. At that point, he repeatedly talked over me, read a disclaimer aloud without allowing me to respond, and ignored my polite requests to speak. He then told me he was "ending this relationship," said he would block my number, and abruptly hung up on me. He did not offer a full refund--only an unspecified portion of what I paid. I uploaded a photo of the revised invoice he sent after damaging my vehicle. In that invoice, he attempted to insert a disclaimer stating that I would accept a partial refund only after he decided whether he caused the damage. The document does not specify any refund amount. Had I signed it, I would have forfeited my right to a full refund. After my Yelp review, I sent James videos from a Tesla-certified mechanic explaining exactly what he did wrong. He incorrectly reattached the wiring, connecting the liftgate to the speaker system, which caused the loud horn noise. On a Tesla, this sound is a safety alert indicating faulty electrical connections. James presents himself as an honest professional. My experience was the opposite. I was spoken over, yelled at, threatened with being blocked, and treated with hostility when I simply asked questions about the damage done to my vehicle. I have never been treated this way by any business before. Based on both his conduct and the documented mechanical errors, James is not qualified to work on electric or modern vehicles. His behavior was unprofessional, aggressive, and manipulative. I strongly recommend that anyone with a newer or electric car take their business elsewhere. Quantum Mobile Mechanic is not on Better Business Bureau. I reported him to the BAR (California Bureau of Automotive Repair).***

    Engine bay post service
    Aiden ..

    I found James on Apple Maps for local mechanics, and boy... I got lucky. I called the number on Apple Maps to see about a transmission fluid leak. James answered with a congenial and professional attitude. He came out ASAP to do an inspection and was immediately able to determine that my transmission was fine; however, I had a bad, leaking valve cover. He charged $100 for an inspection, which acted as a discount when I proceeded with the repair. Since the manifold was being removed to access the valve cover, he asked if I also wanted to get my sparkplugs/coils serviced. He didn't try to sell me on any extra services; he was genuinely interested in taking care of my car. I got my sparkplugs replaced, ignition coils replaced, and a full set of fresh valve cover gaskets with parts+labor totaling ~$900. My 2010 Nissan Xterra with 130k miles has been driving great ever since. James is an honest mechanic who has a passion for treating cars right. His prices are extremely fair, and I would recommend him to anyone in the area.

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    26 days ago

    Fast and quality work. Would avail his services again if necessary. Great pricing too.

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    10 months ago

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    6 months ago

    Fast and very communicative. The owner is transparent and honest. Made my final decision to buy a car because of these guys. Thank you!

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    7 months ago

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    8 months ago

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    7 months ago

    Excellent same day service!! Jacob changed my brakes in a hour. I was very pleased with their service. Highly recommend

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    7 months ago

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    11 months ago

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    8 months ago

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    9 months ago

    Prompt and knowledgeable. Set us on the right track and would definitely hire again to help us out.

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    James W.

    Thank you so much. I'm extremely glad you enjoyed the service!

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    1 year ago

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    3 months ago

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    7 months ago

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    Quantum Mobile Mechanic Reviews in Other Languages

    Ask the Community - Quantum Mobile Mechanic

    I need a 2018 Toyota Highlander Hybrid diagnostic for a hybrid system malfunction. Can you guys come to Lake Arrowhead, California?

    We don’t charge a travel fee if the vehicle is near Pomona. However, for that area we do charge a travel fee. I’ll need the exact address to calculate it.

    I have a 88 Toyota truck that is not getting any electrical power to the dashboard or ignition . I'm not available until evenings after 530pm?

    No problem! We charge $125 for a diagnostic.

    Hi James. I read you're a veteran Navy guy. Me too. Anyways, I have a 1991 Ford Bronco with a 351 engine. I've been eating batteries so I suspect my alternator is bad. Would I be able to schedule with you to come to my house in Claremont fix?

    Of course we can perform a diagnostic for you for a cost of $125. We service the Claremont area. This will include testing your charging system and if you have a parasitic draw we can check that too.… 

    I was wondering how much it would cost to come out and find out is wrong with my car?

    We charge $125 to perform an at home (or anywhere) diagnostic.

    Don’t See Your Question? Ask Away!

    Review Highlights - Quantum Mobile Mechanic

    James diagnosed and explained every part of the repair, gave me options and never pressured us.

    Mentioned in 108 reviews

    Read more highlights

    H Car Repair

    H Car Repair

    (116 reviews)

    Last week my Granddaughter called and asked if I could go with her to the car dealership to have…read moreher car serviced. She has had trouble with the dealership in the past. I live in San Clemente and she lives in La Verne which is about 75 miles away for me, no problem I was at her home @ 8am. I explained to her that I used to have my vehicle serviced at H Car Repair and should give them a try. Ok Grandpa let's go she stated, about 7 minutes away arrived and I let her explain what service she needed and any problems she is experiencing. A very proud Grandpa as she spoke with the owner-manager of the shop. She and Dave agreed to have the work completed. So she and I went to have breakfast and enjoy each other's company which was wonderful to catch up. A couple of hours later her vehicle is ready, Dave brought in the parts replaced into the lobby showing my granddaughter and explaining in detail the process and cost. It was a win win overall H Car Repair has a new customer and Granddaughter now knows that she can go have her car serviced without being taken advantage of at a fair price. 5 STAR SERVICE GRANDPA HAS NOW DONE HIS JOB, THE LITTLE BIRD HAS LEARNED TO FLY ON HER OWN ! Don R.

    H car repair was recommended to me by a friend who has her car serviced several times…read more I went in and basically said I need a second opinion Dave, said no problem he looked it over and told me what was wrong with my Honda Accord. He dealt with the warranty Company and got things taken care of. Dave and his wife were friendly and kind to someone who was taken advantage of at the dealership. Thank you Dave and the H car repair team.

    Quantum Mobile Mechanic - autorepair - Updated August 2026

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