Is a car diagnostic going to tell me what's wrong?

Question

I have only had one car diagnostic in my life and I am not sure it was worth it. Basically, the mechanic asked me what was wrong with the car, I told him that my check engine light was on and throwing codes for O2 sensors and vacuum leak. Then he came back saying that it was the O2 sensors and vacuum leak - not work $79.99 in my opinion. I got that info from Autozone running the check engine light codes.

So, now I've found who appears to be a good mechanic and I am ready to start getting this car worked on (I've already had him fix the vacuum leak). The car is throwing the same codes, but I want to know everything that is wrong with this car so that I can specifically know what I've gotten fixed, what needs to be fixed, what I'm asking him to fix and what I need to start saving for (it's an '04 BMW 325i). I figure a diagnostic would tell me what needs to be fixed, but if all it is is getting an OBD II reader and going down the list of codes, I don't want to pay good money on a diagnostic.

What does a diagnostic entail? Is it just confirming check engine light readers list? Will it tell me about fuel issues (fuel pressure problems, oil leaks, etc)?

Thanks in advance for your help!

Answer 1

the skill set of the mechanic, the data system he uses, the type of scan tool used, and the amount of time that diagnostic charge pays for. all of those influence what you get.



eg: most usa shops use either mitchell or alldata - but the better shops use the factory data system like here

http://straighttalkautomotive.com/software/fsm/bmw.html



as to checking fuel pressure, oil leaks and things of that nature, most likely you would want to discuss a full (or used) vehicle inspection with the mechanic to get all those extra concerns addressed



your car is a 9141/14230 communications protocol and as such most scan tools pull data very slow, however a scan tool that pulls the data faster gives you a better picture of what is wrong

http://straighttalkautomotive.com/tools/generic/scan_tool_usb.html



you could read these specific articles and they will help you more



http://straighttalkautomotive.com/articles/car-scanner-should-I-have-one.html

http://straighttalkautomotive.com/articles/scan-tools-what-can-they-do.html



or you can read all the articles that you need as you need to know more



http://straighttalkautomotive.com/intro_articles.html

Answer 2

What a "diagnostic" consists of can vary widely depending on where you get it done.



Most any auto parts store can do a basic code retrieval for you which will tell you where to begin looking for problems.



No code reader or scanner can tell you with certainty that a particular part is defective.



It requires testing to determine that and all the needed cleaning and test procedures are available online.



The only way to know what a diagnostic consists of is to ask the person performing the diagnostic.

Answer 3

Car engine diagnostic is free in auto zone and Pep Boys and some others auto parts, now you have to check is they still giving this service for free, this sensor usually is located further down the manifold between the catalistic converter and the manifold, it is screw it in, with a wrench you'll be able to replace it yourself, other thing you can try is buy an air flow sensor cleaner, this pert probable is dirty, this will trigger the engine light, look for instructions and video on how to step by step, only use air sensor cleaner and don't touch the internal parts, this will damage it since is very sensitive, good luck, hope this help you some

Answer 4

Any mechanic who charges $80 for just a code read is a crook. When a real mechanic attaches a scan tool they check for current codes and pending codes and history codes. Then they switch to Mode $06 and read what the code data is really saying. Next they look at MAF sensor readings, O2 sensor readings, short and long term fuel trims, EGR commands, and temp sensor readings--all at different RPMs



Just like a doctor interpreting multiple test results, a good mechanic and narrow down their search by comparing all the numbers.



A lousy mechanic reads the code and replaces whatever part name is mentioned in the code.

Answer 5

Why not just get a diagnostic code scanner. The better ones can both read and reset codes.

Answer 6

Car Diagnostic Tool, Obd2 Scanner, Obd2 Bluetooth, Launch X431 Tools etc at the best price supplied from China and shipped to worldwide. Welcome to buy.

Answer 7

You can take it to a dealer and have them run an advanced diagnostic scan, it goes more into detail.



http://www.youtube.com/watch?v=F8__hNZTKCw