I’ve never seen someone cling so aggressively to their ignorance. By law, the CEL lights up when the PCM detects an error condition that can cause the vehicle’s emissions to be above the standard to which it was certified. You may not be able to notice an occasional single misfire, but the PCM does. A misfire is an abnormal condition that over time can damage other parts of the car, even though you blithely assume everything is OK because the car is “running fine.”
If it was “running fine,” the damn CEL wouldn’t be on.
until you fail inspection and have to stop using the car. Then you have to “egregiously waste money” to get it fixed anyway.
goddamnit. Look, here’s the list of mandated powertrain trouble codes. Let’s pick one: P0017 Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor B) What this means is that the PCM has sensed that the readings from the camshaft position sensor and the crankshaft position sensor are out of sync with each other. So, what is causing the problem? If it has a timing chain, is the chain stretched? Is the chain tensioner broken? If it has a timing belt, is the belt worn or has it skipped a tooth? If the engine has variable cam timing, has the cam phaser failed? Is it just a bad sensor? The PCM has no way of knowing what the root cause of the trouble code is. It only has the feedback from the sensors, and only knows that the signals they’re sending back are out of whack. It’s just a computer, it takes input signals and sends output signals. You need a meatbag with a brain and knowledge to figure out why the PCM says the cam and crank are out of sync.
You forgot slugged oil control valve, or VVT unit because the genius that owned the car either didn’t change the oil, or used the wrong oil, or that the reluctor ring on the cam had slipped, or possibly a sheared roll pin on the face of the cam.
Yup, this shit is so easy we only work 1/2 a day and wipe our asses with $50 dollar bills, cause $100s are the only ones worth carrying.
Just like with any carpentry work, things are fixable. If the screw is in the wrong place it is easy to over drill, remove, and replace. Same with the plate. Usually it doesn’t happen, but when it does there is little harm done.
I find it hard to believe that the codes and such are that hard to find and read. The fact that the government had a hand in developing them certainly suggests they could be, but if this was a fact, there are not many people, mechanics and otherwise, who could master this material.
Reading comprehension doesn’t seem to be your strong point.
As you have been told repeatably accessing the codes is easy, all it takes is a scan tool.
Correctly interpreting the codes and doing the necessary tests, and correctly interpreting the results to determine the root cause of the failure is where the skill lies.
If the codes are easy to access, however difficult to interpret, then what is the benefit of having them. In what way do they make things better than before such devices existed and people had to figure out what was wrong based on, well, what was broken, or not working correctly?
In fact, the earliest versions of On Board Diagnostic systems did not return trouble codes; they just lit up the malfunction indictaor lamp (MIL), and it was up to the owner and his mechanic to figure out what the problem was from there. Systems that return diagnostic trouble codes have only been mandated on all US-sold cars since 1996.
Many times, malfunctions that cause increased tailpipe emissions don’t necessarily result in any symptom that the driver will notice. If you’re wondering what the benefit of being able to read a diagnostic trouble code is, suppose the MIL on your car lights up, and that’s the first inkling you have that there’s a problem. Something’s wrong with your car, but you have no idea what; you don’t know what system, subsystem, or component to begin checking. Wouldn’t you like to have a code that tells you that the problem is confined to the evaporative emissions recovery system, or that there’s a persistent misfire in cylinder 1, or that the signal from the bank 1 oxygen sensor is off-scale low?
You really don’t see the value in having the car give you a very generous hint as to where the problem might be? :dubious:
Based on things you’ve said upthread, I can imagine you saying, “if there’s no symptom that the driver can detect, then why the hell should I fix it?” It’s evident that you’re not terribly concerned about whether your car is putting out excessive emissions or not - but the EPA definitely is concerned, and that’s why these systems are required: to alert the driver that there’s a problem that may be causing excessive emissions, and give the mechanic a head-start on identifying exactly what the problem is.
OMG you’re right! The PCM isn’t omniscient, so let’s get rid of it and go back to sloppy carburetors and points ignition.
look, the codes tell you where the problem is. If you’re expecting the PCM to be able to intelligently figure out exactly what the problem is, then all I have to say to you is “Star Trek isn’t real.”
Before such devices existed, we had sloppy carburetors and points ignition. Plus we couldn’t breathe the air around these things without our eyes burning.
Seriously, you’ve transcended ignorance and gone into stupidity. Jesus fucking christ, if you want your car to be a maintenance-free appliance for 500,000 miles then there’s nothing anyone can do for you.
I would guess (but it’s just a guess) that the government stepped in to standardize the codes and connection port across the various makes so that every garage would have easy access to the codes. That way if your PT Cruiser had it’s check engine light come you weren’t at the mercy of the Chrysler dealer. You could go to any garage you wanted. Without the standardization the individual makers would all have their own codes and their own ports and would all likely have proprietary software and code scanners that would either be very expensive or possibly only available to dealerships. Now, instead of having an $80 diagnostic fee the dealerships could charge much, much more then that since there wasn’t much else you could do.
I assume aftermarket scanners would show up at some point but the manufacturers would fight to keep them off the market. It also wouldn’t surprise me if they had different codes for each model or model year so that you had to buy new software for your scanner on a regular basis.
But to get back to your carpentry example. I can pound a nail into a piece of wood, but I can’t build a cabinet to save my life. The benefit of having them isn’t to make it easier for the consumer to fix their own car, it’s to make it easier for the garage to fix the consumer’s car and ultimately cheaper for the consumer. Actually, really and truly, I think the codes were designed (again, I could be wrong) to catch problems with emissions issues. I think the government was more worried about a bad O2 sensor, a rich fuel mixture or bad catalytic converter. Either way going in to your mechanic and saying “Ummm, the car is making a funny sound, it’s going mmmMMMmmmMMMmmmMMM” might take them 3 hours to figure out by swapping out a few parts and hoping each part fixes the issue. But now, with the code, they can swap out one part and you’re good to go.
…But do YOU know what to do when the code says IAC Valve system fault?
Fixing a car (professionally) is skilled trade. I know you don’t consider it one, but you’ll just have to accept it. People pay money and go to school to learn how to do it. Just because they have the aid of computers to help them with their jobs doesn’t make you should have to pay less.
If someone got a bill from the hospital and called up the AR department and demanded a discount because they used an MRI to see inside and therefore they didn’t actually have to do any real doctor work, would that make any sense at all?
They still give helpful info, and things would be much more difficult without them. And they aren’t generally difficult to interpret for professionals with relevant training and experience.
Answer 1: In what way do X-ray machines and CT scanners make things better than before such devices existed and people had to figure out what was wrong based on, well, what was broken, or not working correctly? Nuff said?
Answer 2: Modern systems are considerably more complex than those of decades ago, the onboard diagnostics (codes, etc.) have evolved hand-in-hand with that. Procedures that were suitable for the older designs are woefully, laughably, extremely inadequate for current ones.
…and this is exactly why. Again, emissions problems often occur without any symptom that a driver will notice, meaning the first (and often) only indication of excess emissions is when the MIL illuminates.
I guess this thread has outlived it’s original purpose and should be moved to IMHO.
I feel that auto mechanics are skilled workers. I feel they provide valuable services and for the most part at a reasonable cost. Unfortunately, I feel the whole OBDC II system is a classic example of government running amok. I do realize that there is a need for clean air, and while I am not happy about shelling out $1500 for emissions controls on a new car I am willing to do so, but I think my charges for a cleaner environment should stop there. As with many decisions the government makes, the first 95% improvement is at a reasonable cost, and each incremental improvement then becomes very cost ineffective. Because of this I feel that anything I spend to bring the emissions back to spec are an incredible waste of my resources. Yes, if I cannot tell it is broke, I absolutely do not want to pay to fix it.
They still give helpful info, and things would be much more difficult without them. And they aren’t generally difficult to interpret for professionals with relevant training and experience.
Answer 1: In what way do X-ray machines and CT scanners make things better than before such devices existed and people had to figure out what was wrong based on, well, what was broken, or not working correctly? Nuff said?
Things are better with such devices, but only marginally. Some things are diagnosed more quickly, but on average, I would think the effect on health care is much much less than is generally assumed. This is statistical. Clearly if a one in one thousand improvement in health occurs to me the value cannot be overestimated.
If you think things are only marginally better with the advent of radiology it’s no wonder you don’t understand OBD-II and how it’s supposed to help diagnose car troubles with the help of a skilled mechanic.
This is serious stupidity. Just had two ignition coils replaced. Now, one week later the CEL has re-illuminated. Fortunately, this seems to simply be a computer problem. I will find ask if Firestone will rescan for free to at least let me know if it is the same problem.
This whole CEL is incredibly annoying. I have a car with 232K miles. That is a good car. But lately, the government has been making me throw away money so I can keep it. First a new Cat Converter so it could pass emissions inspections. Next ignition coils, which most definitely had to be done, but is probably more expensive do to the OMDB-II, and now a hopefully harmless light, but still annoying.
Does anyone think that the good of this system outweighs the harm done to me personally?
The CEL is annoying? The CEL harmed you? It saved your new catalytic converter from being destroyed. If you don’t like paying for the scan, find a shadetree mechanic who will fix your car from the seat of his pants, and avoid the big corporate guys like Firestone.
For better or worse, society demands that cars be in good enough repair to not dump massive amounts of crap into our air. The CEL and ODB-II help make that happen by informing drivers when repairs are needed, and giving mechanics raw data to help them determine the root cause.
Your entire premise is absurd. The emissions inspections are not required in most of the US. Cars are not dumping massive amounts of crap into the air. I think that paying for all these emissions devices as an ad on to the price of a car is going way far enough. Spending a small fortune to keep them working is damaging me without really helping anyone.
And I do not like paying for the scan for several reasons, not the least of which is that most times the light comes on there is nothing wrong with the car. Just like people, if it ain’t broke don’t dare try to fix it. You will just screw something up.
I will rescan for free within 30 days, and agree/hope Firestone should do likewise.
The OBD-II doesn’t make it more expensive, assuming you mean more expensive than doing an analogous repair on older vehicles. It’s the overall design that makes it more expensive, in this case having one ignition coil per cylinder rather than a single coil for the whole engine. Of course with the single coil, it was necessary to have a distributor and spark plug wires, which represent potential repair expenses that you will not have on your car.
Well, obviously you don’t. But please consider this perspective: As I mentioned, it’s the overall design that leads to certain repair situations and expenses. One goal of this design is to control/minimize tailpipe emissions, for the public good. But along with that goes enhanced performance, better fuel mileage, and better overall reliability. “Back in the day” it was necessary to replace points and spark plugs approximately every year, 10-15K miles, and it wasn’t unusual to need to adjust points and clean plugs between replacements. Now, electronic ignition components give trouble-free performance for years. Replacing coils after 200+K miles compares rather favorably with replacing points 15-20 times during that same period. Spark plug replacement intervals are at least 30K miles, with more and more vehicles it’s 60-100K miles (depends on the particular plug design used).
The OBD-II system is the controller and watchdog of the overall design here. Blaming it is rather like killing the messenger. Aside from its annoying use of the CEL, it does a remarkable job of keeping everything working smoothly and efficiently. Your mention of “nothing wrong” might be more accurately rendered as “nothing wrong that has to be fixed for my car to run acceptably.” However, there is something wrong in terms of some polluting being done, and the cumulative effect of that little bit of polluting multiplied by millions of cars over many years really does add up. It can be hard to really grasp how much public good has been done by cleaning up car exhaust because we haven’t experienced how awful it would have been if the U.S. had not enacted pollution controls. One might look at the situation in China to see what we have been spared. You and your loved ones have benefited from this. I disagree that keeping your car in spec is unfairly punishing you while doing no good.
But please consider this perspective: As I mentioned, it’s the overall design that leads to certain repair situations and expenses. One goal of this design is to control/minimize tailpipe emissions, for the public good. But along with that goes enhanced performance, better fuel mileage, and better overall reliability. “Back in the day” it was necessary to replace points and spark plugs approximately every year, 10-15K miles, and it wasn’t unusual to need to adjust points and clean plugs between replacements. Now, electronic ignition components give trouble-free performance for years. Replacing coils after 200+K miles compares rather favorably with replacing points 15-20 times during that same period. Spark plug replacement intervals are at least 30K miles, with more and more vehicles it’s 60-100K miles (depends on the particular plug design used).