hi sages- been trying to figure out how an O2 sensor works. in two of my cars the service engine soon light came on. not wishing to pay the dealer $90 to just plug in his obd sensor, i replaced the O2 sensor and the light went out and has stayed out. engine ran fine before and after the sensor was replaced(88 buick). on my other car(00 sebring) the sensor light came on on a recent trip to key west(5hrs, 65 mph). this was the first long trip in a long time. most trips in both cars are in town and short. on the way back from key west, the lightwent out and stayed out. i remember the sensor i took out on the buick. it had a sooty bulb on the end that was silverish when i rubbed the soot off. the sensor senses the amount of 02 in the exhaust and then signals the computer to make the mixture leaner or richer. if the sensor goes bad, the computer is signaled to make the mixture unnecessarily rich. the sensor senses the concentration of hc in the exhaust. im guessing the bulb somehow reads the hc/soot in the exhaust by sooting up the bulb or somehow sensing the temp of the exhaust. also when the sensor craps and the mixture is made richer, would gas miles necessarily drop? thanks in advance for giving me a quick class in these dealer profit enhancers. paladin

Yes O2 sensor sniffs O2 concentration and adjusts fuel injection for correct mixture. When the sensor goes bad your engine will run rich, and can make for poor fuel economy.

Check engine light can mean a bunch of things other than an O2 sensor problem. Common one is fluid leak caused by the gas cap not being closed properly. By turning the ignition key on than off then on etc. per owner's manual on Chrysler products one can retrieve trouble codes.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Some auto parts store chains also do free code readings.

Yeah, the parts chains will usually scan you car (with a cheap, generic code reader) for free and happily sell you a (generic) part that's probably in stock (cheap) you can install and (maybe) fix your car(for now.) When the light pops back on with the same code and you go back they may even give you another part for free thinking the last one was bad. It may take several tries before you wind up at a shop with competent techs using factory parts who will diagnose fix it right the first time. Good luck.

-James

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Hey, I didn't say it was the best approach in the world. But for someone thats mechanically inclined and doesn't want to pay just to have codes read, its not a bad alternative.

88 still makes it OBD-1 right?

yes pierre i think thats right. the autozone didnt have a scanner to check a vehicle that far back- 88. said they could only check a 96 and up vehicle. dealers and clipper mechanics here wanted 90 to check it out. like when you need an appliance repairperson . they typically want a c note just to come to your door. dont mind a single or a double, but tired of these characters having to make a homerun on every pitch. in this economy you have to save your pennies and save your dimes if youre going to buy a 409. to keep your wallet off life support you have to learn how to fix as many things as you can yourself. more shysters out there than ever now. anyone fallen for the old oil change special yet? get your oil and filter changed for only 12.95 and with it a list of discoveries of must do safety repairs that they can fix right now for only $899. i can remember uncle moe in 61 saying what a helluva racket. regards and be careful of those who will pat you on the back with one hand and pick your pocket with the other.

Like I said, save yourself some time dough and find a decent shop that can fix it right the first time. It may take some doing, but they're out there. The big chains aren't it, by the way.

-James

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Oh Bob, I almost forgot. How long do you think any repair shop in any economic climate stay in business if they just diagnosed vehicles for free?

-James

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Hey Bob,
Maybe you can use This
Hope this helps


Dave

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81 Dodge D150
It looked easier in the book .

hello james L- never would expect any repair shop or anyone in business to do something for free, unless it was a tiny job for a good customer which was tied to a previous job paid for. the problem is 90 for a diagnostic test which takes less than 10 minutes is a clip by any standard. the standard should be what is reasonable. many dealers, mechanic shops and specialty shops near me have closed in this economy . while not the only factor, you cant tell me that shysterism. overcharging the consumer and poorly designed cars that lend themselves to expensive repairs arent partly at fault for these business failures. im a very old man and have been watching this since ike was president. consumer disgust and anger particularly with cars is worse than i have ever seen it . this country and others are building the wrong kinds of cars and people arent buying them. wondering when this is going to turn around. soon i hope.

With a diagnostic scanner (not a code reader) that has a cost of $5,000 plus.
This cost must be recovered. I charge $50 for a scan. If I do the repair, I give a $25 credit toward the scan.

" I didn't design it, I didn't build it, and I didn't break it, but I most likely can fix it"

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

charlie- not sure i buy your economics. that 5000 machine surely has to engage cost recovery, but i think thousands of gm cars will go through that machine over its lifetime, most of which will lead to an expensive repair charge. by the way i think the 90 i quoted was for a code reader at the dealers. this is what i meant by too many having to make a homerun on every pitch. at the very least the dealer or mechanic should absorb the argumentative charge for the code read if he gets the repair job. its a 10min. job ive seen it done. if a dealer clips 90 for a 10 minute job, thats $540/hr for that machine.even welders only want $300/hr and i thought they were the worst. the cost would be paid back in 10hrs of use. sure would hope a 5000 machine would last more than 10hrs. besides at least half of the customers would go for the repair suggested dramatically enhancing dealer profit. now heres a good riddle for you,too many times in these cases i have seen a code readout check, followed by a costly repair and the car still runs as badly as it did before the code read. there is too much of thisgoing on in the car business today and i think consumers are fed up with it. ill stand by my point, but appreciate your input. bf

Bob, I'm not in the car biz, but someone here that is can confirm the high cost to up date those scan machines yearly. I'm talking thousands of bucks annually to have current soft ware to work on all makes & models.

The other problem garage owners have is someone brings in a car, gets it diagnosed, and goes home and fixes it under the shade tree. Not only is a machine used, but a bay has been tied up for a minimum of 1/2 hour, a trained mechanic has also contributed his knowledge & training into the mix for that half hour. Than shade tree man talks the mechanic's ear off for another half hour asking how to do the job, with most likely a follow up set of questions the next day. You have to realize that the dealer, or independent put that machine in for their use, not to provide a service like a lending library.

I think 90 bucks to get to the bottom of a problem one was not able to figure out how to fix on his own is cheep. How many times have you had the pleasure to throw parts at a problem to the tune of several hundred bucks, and still not solved a problem? When I had my locksmith biz, there were people that would come in and pick my brain, waste my time, and go home and try to fix their problem. I can tell you if I had to go straighten out one of these home grown messes I got paid real good, a lot more than if the guy had just called to have me go fix it.

These new cars are not built like the ones we were, oops... are, in some cases here, driving when Ike was warning of the Industrial Military Complex. It takes a lot of training, and studying to understand how a modern automobile's inner workings work.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Bob, a code reader in not a scanner "scanner". A code reader is just that, it will only read codes. A scanner will show the info the computer "see's" and the also it's out put. A example of the two is:

Check engine lite on, and code reader says the code for O2 sensor not switching. Is it a O2 sensor problem or something else.

A scanner might show the the fuel trim values as being high, with the computer, trying to richen up the mixture. Could be low fuel pressure, or a vacuum leak, and not even a problem with the O2 sensor.

Another example: Car runs poorly, mostley bad idle, and poor fuel mileage. No check engine lite, or codes set.

With a scanner, the data shows coolent temp at -32 degrees. Problem is with the coolent temp circuit. Will not set code, as -32 is a valid number. But the fuel mixture is very rich, like a carb car with the choke stuck on..
(this is on older cars only. newer cars will set a code, as the computer will look for a temp increase over a time span.)

A scanner or code reader is just a "tool", the operator still has to know how to interperate the data.

If the shop you go to is trying to charge $90 just to use a code reader and tell you the codes, go someware else. If they are using a scanner, and doing a diagnostic check, they are not out of line.

The auto repair industry screwed up big time, back in the "80"s, when electronic controls started coming into use. They didn't educate the public on what it cost to service these vehicles. These costs are not just equipment, but also training expenses. I am retired, and cannot afford to go to many of the training courses, working part time. I still spend about 40-80 hours per year, going to the few free, or lower cost traing courses.
I also hear people complain about having to pay $xx per hour to the mechanic/tech. but how many other "trades" require the worker to have an investment of $50-$100,000 in tools.

OK, off my soap box.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

hi wjar and charlie- wjar find i agree withmost of what you said. charlie you hit the distributor square on the reluctor in your paragraph 7. a dealer did try what you described, must have thought i was dumb, so i in fact did just what you said. am a very sensitive guy whose feelings get easily hurt, but i recover quickly. you make a very good point about failure of the big companies to prewarn or educate the consumers about this kind of thing. these kind of computer and electronic management conundrums are more expensive to diagnose and fix and for what real benefit. gas miles and emissions are said to be the benefit. where is the benefit when presumed gasmiles savings are more than eaten up in unreasonable repair costs. heres a good one from recent personal experience-$ 800 to diagnose and replace a distributor in a non running 2.5 v6 sebring. cmon, i could have done the diagnosis and replacement in my sl6 80 volare for 25. both cars get 20mpg. not in the sebring with sensors, computer, electronics, temp circuits. i could go on with the folly of interference engines and internal hydraulic clutch slave cylinders. these improvements to me and others are not improvements at all. but steps backwards because they only reallyserve to enhance dealer profits by further limiting self repairs . soon i expect to see a new car the shade tree mechanic cant even change the oil in because the procedure will have become so complicated.heard that bmw a car never known forreasonable economical operation soaks the owner $1000 for an oil change filter and lube plus various and mysterious fluid checks and adjustments. find that hard to believe, but even if its only 1/2 true, its still a ripoff of the public and close to consumer fraud. charlie and wjar, just think of the great number of consumers out there who unlike the three of us lack the knowledge and experience of these ripoffs and get slaughtered by the thousands each day. if that money could be saved for just 3 years our current debt might be zeroed . exposing scanner tricks alone might put themortgage crisis in the black(only kidding). tell me where im wrong. regards bf