When you pay for a diagnostic, or service work, what are you paying for?

Having first hand knowledge of some recent incidents, I am forced to ask the following questions, and would love to read your thoughts. When you are paying for diagnostics, the assumption is that the diagnosis is correct, so you can make intelligent decisions about what to do next, right? example: someone had a rattle coming from the passenger rear of his 996.1. As someone who has driven a half million miles and probably 100 cars in his lifetime, from first gen Mitsubishi Colts to F1 cars in corporate sponsor events, with a few Lambos Ferraris Porsches and other interesting makes and models thrown in for variety, he would almost lay down money that it was a loose rattling heat shield. It sounded just like the 5 other "loose heat shields" he'd experienced in the past many decades. He takes it to his then current Porsche indi (a shop that crews several 1st place winning Cup cars as well as maintaining many local interesting street Porsches) and in 5 minutes, using the famous "hammer test" and "boot test" the shop manager states unequivocably, "it's the cat." "are you sure? it sure sounds like a heat shield or some other loose attachment." returning to the shop when the owner is in, the owner starts out saying it might be something else, but after talking to the shop manager, agrees "it is the cat. we've done so many of these, we know..." Not completely comfortable with that diagnosis (maybe because of the $2000 + bill that would entail for a new cat - one side only! - and labour) he then took it to the shop he previously used. They charged him $99 and concluded the same, "it's the cat." So biting the bullet, he bought a cat for nearly $2000...while waiting for an open time in the shop to put on the cat, he bumped into an old friend who crew chiefs for another very successful racing team - VARA, NASA, Continental Challenge, ALMS, et al - and who is highly regarded by specialists. This guy runs a one man shop and takes in referrals... He has an opening that weekend, and the 996.1 and new OEM cat is brought in. Putting the car up on the rack after allowing for the exhaust and motor to cool down, the first thing discovered is a broken bracket for the last part of the exhaust plumbing, allowing for some play between bracket and pipe. The mechanic then puts a stethoscope to the cat - there is a VERY VERY SOFT rattle from the cat, certainly nothing like what was being heard that started this whole misadventure in the first place, and not like what was heard during the "hammer test" and "boot test" performed by the two previous shops. Since the cat is bought and in house (again, new, OEM cat) and since there is the minor, very light rattle heard through the stethoscope, the decision is made to change the cat anyway. Guess what? Gas mileage goes up. The rattle changes a little, at first, from what was heard inside the cockpit before the cat was changed. So ok, maybe it wasn't the cat causing the rattle but the old one was going so ok, c. $2000, bullet bit. Of course the old cat was returned to the owner ("keep the old cat, it's most likely still good and you can put it back if the new one goes bad") !?@?!>%! Over the next 400 miles, the rattle is back, worse than ever. So obviously the original rattle was not the "bad cat." So the question - When you pay $100 for a diagnostic (or even the free but adament one) and it leads to spending $2000 for a part and labour, and it doesn't fix the problem, even clearly WASN'T the problem, What would be going through your mind? Is this "just the way it is?" grin and bear it? go back and raise hell? Interested to read your thoughts on this, even if I / my friend are missing something. End part 1 / scenario 1

Did "he" take a test drive with the tech and reproduce the noise with the tech and agree that WAS the noise he was talking about? Or it's just a description of the noise and then hand over the car to the tech?

the first shop never went for a test drive; he jacked up the back, did "the boot test," and drew his conclusion as gospel. the second shop, the one that charged for the diagnosis, had a mechanic go for a test drive with the owner, where the rattle of course didn't express itself. Then the shop manager went for a ride, and something similar (but not exactly what the owner was complaining about) was heard. Then it was put on a rack and "the hammer test" was applied and conclusion drawn. The funny thing is, the later discovered broken bracket by the shop that did the work was the cause of much (but not all) the rattle.

Well, for any given symptom, there may be more than one possible cause and therefore at least that many ways to fix the cause. I think in addition to the diagnosis of the potential causes, you are paying for advice/strategy on how to proceed. That's an evaluation of the costs of the potential fixes weighed against the likelihood that each fix will indeed cure the problem. So, you would hope that a cheap/easy repair would also have a high likelihood of success. Although the cat fix may have had a high likelihood of success, it was also very costly. The rattling heat shield/broken bracket may have been seen by the techs as having a lower likelihood of success, but since the cost was a tiny fraction of the new cat, they should have spent half an hour of your money eliminating that possibility first.

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and the "rattling heat shield" possibility was dismissed as "there is no heat shield to rattle on a 996" so based on those comments, and how vehemently both shops were sure it was a bad cat, that was the only way the owner went, even though he was still sure it sounded like a "loose heat shield" - he's heard bad cats, and it didn't sound like that (even though admittedly he's never heard a bad 996 cat...)

The heat/splash shield over the coils can produce a loud rattle, especially when the section directly under one of the bolt heads corrodes through and only one bolt is actually clamping the shield.

I don't think either shop has decent diagnostic capability. The broken bracket should have been discovered by a simple visual check. 996 has heat shields, in fact full of them surrounding the cats and the mufflers, all behind the rear bumper. They should have condemned the cat(s) ONLY IF they heard the noise when engine is running and they also verified it by using a mechanic stethoscope on the cat(s).

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which will be in a few months for OFL. Any thoughts about diagnostics? I'm just trying to get a sanity check - diagnostics charges are for time spent, even if the diagnostics are wrong?

But why start a 2nd thread?

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Now that you point it out I see your point. i"ll delete the other thread. So any thoughts on the topic? Is the bill, diagnostic or service, for the time spent in the effort, or is there any expectation that the diagnostic and corrective service are "correct?"

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If you had a new and serious medical condition, would you expect your doctor visits to be free if you had to go back several times? The shop has to pay their employees. If you have a hard to diagnose issue with multiple possible causes, it is unreasonable to expect the shop to divine the issue the first time around. It sucks, but that's how it goes. Now if the shop is incompetent, that's different. But no, I do not assume that a diagnosis is a guarantee of a cure.

Reads like someone paid $100 not for a diagnosis but for a wrong guess. My opinion is one needs to find another shop. One that charges less for the wrong guess or is better at guessing for the same money.

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Hi, 5CHN3LL i'm glad you brought up the medical example. my father was diagnosed with stage 4 cancer and given 6 months to live. Part of the treatment was to remove as much of the cancer as possible, so snip snip and much of his colon (excuse any medical impreciseness) was gone. A few days later he complained of extreme abdominal pains, exhibited distention, and returned to the hospital. He was poked and prodded and told to go home and rest with a prescription for pain. Two days later he returned to emergency - after more extensive diagnoses it was discovered the sutures were leaking; basically his **** was spilling out into his abdominal cavity, resulting in distention and an infection. Diagnoses is not a precise science; more often than not there is a large element of intuition and art, absolutely agreed. But you mention incompetence; help me understand incompetence and the thresholds thereof, please. My father didn't die from the abscess and infection, thank god, succumbing to the cancer 3 years later, though he did have to suffer through 5 days of excruciating pain - in the end he had a 6 inch - SIX inches - distention, with fevers and regional infection. In the 996's case. It was a c. $2000 cat replacement that wasn't necessary, which, apparently, a mech stethoscope might have confirmed or disuaded. Does that count as incompetence? i'm not trying to rhetorically force a conclusion, I'm trying to triangulate the range of reasonableness. Thanks!

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Lol your suggestion for finding another shop. How to do this a priori without discovering this through an expensive mis diagnosis / guess?

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Well, it can be hard to "qualify" a shop. I tend to avoid indy shops. I know many favor them and there are some good ones around but my experience with indy shops prior to my Porsche experiences was not good. In fact it was so bad I began to work on my own car and did so for several decades, even advancing to engine rebuilding. When I first came to CA with my Porsche I used one indy shop for a job and the work was good and I liked the service. I decided to use this shop again for an oil/filter service. But before dropping the car off I was talking to the owner and he told me he insisted on using 15w-50 oil in my Boxster. I noted this was not the correct oil and could I bring/supply an approved oil? He said "No." He went on to say he needed the markup of the oil he supplied to help his bottom line cause his prices were so low. Well, one is his prices were not that low. Two I see no benefit in having my car improperly serviced just so the shop owner has a better profit margin. I no longer use this indy. Almost 100% I rely upon a dealer to service my cars. The techs handle the little jobs, even the jobs that are done free -- like today I had a new rear view mirror installed and the tech took special pains using a special vice grip -- made for this job believe it or not -- to remove the mirror to avoid any risk of fracturing the windshield glass -- and the $3000+ jobs that was done some 6 months ago: A new water pump, T-stat, fresh coolant, radiator fan motor, idler and tensioner rollers, and new front diff axle flange seals. It is kind of funny but once in a while when I ask for the old parts back -- I like to study them and see if I can figure out what went wrong and why -- and the tech will ask me "Don't you trust me?" I tell him that if I didn't trust him I wouldn't even be at the shop asking he return the old parts to me, I'd be at another shop. The techs take the time to go over the job with me, that is the more complicated ones, like the work on the Turbo, or when I had the Boxster in for a new VarioCam solenoid and actuator. Take that back. They have in the past gone over the simpler jobs with me, like early on oil/filter service which is more than just draining the old oil and dumping in new oil, or more recently, like today now that I think of it, the tech taking the time to explain the issue with the rear view mirror removal and installation and the control button on the side of the mirror that controls the brightness of the comfort light that is housed in the mirror, a control button that I didn't even know existed until today. If there is a problem the tech will tell me how he intends to work towards a diagnosis. Now I don't get an auto tech education every time I take the car in but I spend enough time to get a good feel for the job, what's involved at least at a level I'm comfortable with and believe the tech will arrive at the right diagnosis.

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EXACTLY! this IS the way it IS, Like it or NOT!

Between Macster and the medical analogies I think the issue is well sorted. Each owner is the best expert on their own car...they do all the driving. A good mechanic will listen to what you have to say because you are an important source of information. Fancy race car resumes don't mean a wrench is good for your car and its needs. Often they are bored by the mundane day to day car maintenance issues. I also am happy with dealer service on my '03 996. Yes they are expensive. However they take their time to listen to me and they keep me involved in what they are doing. So far I have no complaints.

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I'm still waiting for a definition of "incompetent"

**** happens

Incompetent: I used the wrong length bolts when I reassembled your car and a piece of the block broke off and was ingested by the internals. Not incompetent: My car is rattling. Shop: That can often mean the cat is bad. Me: OK, if you say so. Go ahead and spend $$$$ on fixing the most expensive potential part. My 996 had a rattle that I thought was the cat - so I pulled the cats off and replaced with cat delete pipes. Still rattled. Banged on a few heat shields. Still rattled. Assumed it must be the muffler, so traded my rattly mufflers for another member's used factory mufflers. No more rattle. Had I been paying a shop to do all of this diagnosis, there's a good chance I would have wound up paying for new cats, since they can't legally do what I did. It would have sucked, and I imagine my indie would have given me some goodwill toward future labor, but I wouldn't assume the work and parts should be free simply because they replaced a known-to-fail part as the first troubleshooting step. Ultimately, the decision to raise hell depends on whether you want to continue working with the shop. Since that sounds like a "no," go in and freak out. If the answer was "yes," explaining your concerns to the service writer is probably going to work better than raising hell. Raising hell works well if you can bully the other party, and regrettably mechanics are sometimes less susceptible to this than, say, the guy at the Apple Store "genius bar."

My wife had back pain, mri shows disk issues, surgeon says she needs a cage around her spine to prevent greater damage. She goes to another doctor, he says lets go slow. No surgery. Physical therapy. A little improvement. Six months later in an unrelated medical blood test she has to stop all medication for the test. This includes the medication to prevent osteoporosis. Amazingly, all pain disappears. Doctor says the pain was probably being caused by the medication since this is one of the potential side effects. Bottom line...nobody was incompetent...all saw the issue from their own point of view. Bottom line...some days you are lucky and some days you are not.

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I wasn't looking for encouragement to raise hell or not, just trying to gauge a range of what is acceptable or not among "old timers" and of course, those who DIY. I personally feel, if mechanics stethoscopes are common tools to diagnose "noises" and "noises" are a tell tale symptom of a failing cat, that it be entirely reasonable to expect a shop to use this tool to confirm the diagnosis, for such an expensive problem, ESPECIALLY if they are going to charge for the diagnosis. If it was a 5 minute curbside consultation, no bill attached, then there is much less to no expectation of "further investigation" - "ya get what ya paid for" <shrug> ps: the diagnosis was not "that can often mean the cat is bad" it was, "The cat is bad." There was no room for error or interpretation in the diagnosis, no "it's your call." But then, I'm getting the feeling many of the respondents feel the burden of responsibility rests with the owner, which I agree with - afterall, I own and drive a 996 too. If the engine blows, or the IMSB fails, it was MY decision to own and drive the 996.

I just got stuck by a dealer from another marque. 850 bucks for them to keep the car for 3 weeks easter egging around and not finding the problem. Once I got the car home I changed out the high pressure fuel pump whala fixed. then as a result of them dinking around must have crack the plastic valve cover. 350 bucks later the air leak upstream of the throttle body is fixed. intgrated PCV is a dumb design So yea the current crop of wrenches out there are not that hot.

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BMW N series motor by chance?