Join Date: Jan 2011
Location: I would rather not say
My point was that there are pros and cons to trying to do it yourself.
Alexie - You think "The fault codes normally tell you exactly what the problem is, there is no "interpreting" .... err that's the whole point of them". Not so, and this is my point. There are many codes which need to be interpreted in order to make the correct diagnosis. Take P0170 Fuel Trim Malfunction for instance - what part are you going to replace yourself to fix this code? The point of my post was to present a balanced view. You can buy a cable yourself, you can read the codes yourself, but making the fix it isn't just a case of acting on fault codes.
Many codes which are flagged, even codes which relate to a component, may not relate to the component failing, but could concern the connections, wiring, or the thing they are measuring (water/air/engine position).
Quality comes into in it in the way that most ELM based scanners and software interrogate the EOBD element of the cars computer (this is aimed at flagging emission related issues). The vehicle manufacturer arm the cars computer with an additional level of so called self-diagnosis, which is designed to be interrogated by manufacturer specific level tools/software. Also, higher quality tools/software allow the user to view live data stream at a high resolution, This means faults that haven't set a code can be investigated.
There are many garages out there who don't have a clue, and would just act on the fault code. My point is a switched on garage will perform diagnosis, not a code read - two very different things. The garage or mechanic that can diagnose effectively will deliver a more economical repair.
You say "There is no reason to throw parts at the problem any more than some average garage mechanic would do if the results weren't absolutely definitive." There are many drivability symptoms (flat spots, hesitation etc) may not even produce a code. Some components, such as the MAF sensor, even when they are on their backside, wont set a code. If you are relying on a light to come on, and a code reader to suss these problems, even the worlds best code reader is less use than a motorcycles ashtray. There will be no code, no light and the car will be driving badly. In this case a simple multimeter will tell you what's wrong.
I understand that you "Really can't see the point of your post at all." This is probably because you dont really understand the specifics of fixing cars.
I hope my post has helped you understand my point of view.