They Won’t Show You the Problem

A good mechanic will be transparent. They will show you the problem and even try to explain it to you. A mechanic who is unwilling to show you an alleged problem with your vehicle is likely trying to deceive you. And if they aren’t actually hiding something, at the very least, they may not know what they are doing. Sometimes, they may show you a broken part, and it's not even actually from your car, so confirm they actually took that part from your car.
Shady mechanics often make up issues with your car when you least expect it. You may be going in for just an oil change, and suddenly, you find out your vehicle allegedly needs a fix that costs hundreds of dollars. In those circumstances, it may be best to get a second opinion.
They Won’t Return Damaged Parts to You

Legally, every part of your car, whether broken, damaged or worn, belongs to you. Some mechanics will give you the removed parts without even asking, but if they don’t, be sure to ask for them. Before you sign off on any repairs, be sure to let them know you want any of the removed parts returned to you. You can also ask for any packaging or containers housing the new parts.
If your mechanic refuses to do this or gets angry at your request, they may sell you old parts or replace something that doesn’t need replacing. You should take your car to a different mechanic.
Chain Service Centers

You may think that a chain service with a reputation to uphold would surely be less likely to scam you, but the truth is that their established reputation makes it easier to get away with dishonesty.
Unethical practices and overcharging for services may be commonplace because they don’t really have to worry about the reviews. Even numerous customer complaints can just be minimized as “a few bad experiences.”
They Recommend Fuel Cleaning
Replacing Parts Without Telling You

Every repair that your mechanic performs should be first confirmed by you. Don’t allow for any repairs without your consent. And be sure to get everything in writing, along with a written estimate of the part and labor costs.
For instance, it’s easy to get conned by a new air filter charge. Many customers have complained about getting charged for an air filter that was never even installed. It can cost up to $100 to replace an air filter. If you install it yourself, it can cost you under $20.
Claiming Your Motor Oil is Low

Rarely, unless there is a leak, will your motor oil levels be on low side. It may be dirty because it needs replacing, but it is not likely to need more oil. Other things they might claim are low include your freon or coolant.
If they lie about your coolant, they may try to convince you to pay for an expensive radiator replacement. They can fake leaks by pouring coolant onto the ground.
Premature Battery Replacement
They Use Cheap Parts
Claiming Your Serpentine Belt Needs Replacing

This one is fairly common among dishonest mechanics. They will claim your serpentine belt needs replacing, even if it is in optimal condition. The truth is that these belts do not wear quickly by any means.
While the cost of this part may not necessarily be as high as other repair costs, the little things can add up.
They Don’t Offer Alternative Solutions

When getting your car fixed, you should never feel like the mechanic has only their best interests in mind. Sure, it’s just a machine, but a car should also be treated with a do no harm attitude. If a part needs replacing and you could easily do it yourself for less money, the mechanic should be upfront about that and not try to milk you for all you are worth.
On that same note, not every problem has only one solution. A mechanic can give you multiple solutions to a problem, even if they are temporary fixes.
They Only Take Cash
They Aren’t Licensed

It should go without saying: you want a mechanic who knows what they are doing. A licensed mechanic has some strong footing if they are, at the very least, licensed. A license says that the mechanic is trained, educated, and certified to handle repairs.
The best mechanics will maintain a continuous education regarding the newest systems and practices.
Before taking your vehicle to a mechanic, always come prepared. Be ready to ask questions and learn new things about your car. Being knowledgeable about your vehicle will go a long way in avoiding potential scams. You can even test your vehicle with a diagnostic scanner, which costs only about $25, and that will tell you what you should expect before going to a mechanic.
