If I have a diagnostics check on my car will the issue be fixed afterward?

Diagnostics check is just that a check to find the problem, in some, or most cases it can be fixed same day depending on the problem, but in other cases may take a day or two.

Only if you authorize repairs after the check and being told what is wrong.

Maybe, but probably not.

Usually the mechanic will call you, tell you what they think is wrong with your car, and give you a quote for those repairs.

Sometimes if its a really simple fix they will just do it. Most shops charge a diagnostic fee that is equal to one hour at their standard shop labor rate. The good honest shops will spend a full hour on your car and if they can find AND fix the problem within that hour without buying any parts they will do so.

As an example I recently took my car to a shop because the headlight wasn't working. I had replaced the bulb but that didn't fix it and I don't have the skill or tools to diagnose more complicated wiring issues. The shop quoted me 1 hour of labor as a diagnostic fee. Their technician was able to identify the problem and fix it within 1 hour and the only parts he needed were a few inches of wire and some splice clips which weren't even worth charging me for (maybe $5 worth of parts at most). So I left the shop with my car fixed and all I paid was the 1 hour diagnostic fee and sales tax.

But that's the exception, not the normal process. For problems more complex than a lose wire they're going to give you a recommendation and an estimate. You can either pay for the diagnostic service and leave without fixing the car, or authorize the repair and pay for the diagnosis and the repair.

Depends on what it is and the plan you work out with them in advance.

Does your 'car' have a make/model? Are you experiencing any actual problems - or just getting lights?

A diagnostics check will tell them what codes your car is throwing, and allow them to reset the codes. If it isn't actually having any problems you can go back to driving it, and see if the codes come up again (you can always buy your own OBDII reader - and pull your own codes).

If it keeps throwing the code - or if the mechanic tells you it needs a specific part/repair, then get a quote, and then call other shops and gets quotes.

DIAGNOSTIC simply means to inspect and find a cause for the problem. If you want it FIXED, you'll have to pay more.

Depends, if the Tech finds something unplugged he'll probably just plug it back in. If he determines that the car needs work that requires any time you will be given a description of the job and the cost before he proceeds.

It depends on what is wrong.

Tell the mechanic what the motor is doing. Don't just say you want a "diagnostic check".

Typically - and required by law in many places - the facility will give a written Estimate of the cost to effect repairs, and owners will sign as a Work Authorization.