On 3/4/21 5:19 pm, Steve W. wrote:
> micky wrote:
>> Are my business assumptions correct?
>> I'm trying to get rid of some engine trouble codes, and I need to
>> install 2 or 4 oxygen sensors.Â*Â* I know I can install one of them, and
>> if I find a place where I can jack up the car and work underneath, I can
>> probably do the remaining 2 or 3. I'd prefer to do it myself mostly for
>> the satisfaction and bragging rights, but also to save money.
>>
>> However if I fail with 2 or 3 of them, I would take them to a shop to be
>> installed.
>> For no special reason except that I think I know how the world works,
>> I've always felt that if I buy parts and bring them to a shop to be
>> installed, the owner will make up the loss in profits on selling the
>> parts with an increased charge for labor, or something, on the theory
>> that the job takes the same amount of time minus 10 minutes to order the
>> parts, and he shouldn't be deprived of the normal income.
>> Is this true?
>> Is there a difference if the shop's owner has a reputation for being
>> honest?
>> Or do honest shops just charge the flat rate for the job and skip the
>> profit they would have made on the parts?
>> If I were in their shoes and I felt obliged to do that, I would be irked
>> by a customer like I might turn out to be, and I might even, I would be
>> tempted to rush the job, potentially making a mistake.Â* Or to skip
>> almost optional things like cleaning up great afterwards, or putting the
>> paper floor mat in front of the driver's seat.
>
>
> Well you can **** money away by changing the sensors but it's not going
> to clear those codes. You have a different problem.
>
> As to what the shop does, it depends on the shop. In mine if a customer
> brings their own parts, they are installed with no testing or warranty
> given because those are the parts YOU want installed. It is also noted
> on the paperwork that "Customer supplied parts installed per their
> direction" That way if the parts are wrong or don't fix the issue it's
> not my problem.
> No difference in the labor rate.
>
> Now a good shop would bring in the car, do an actual diagnostic on it,
> then repair the real issue, which in this case could be nothing more
> than a broken vacuum fitting or bad intake boot that is letting excess
> air in past the MAF. Or a skewed MAF that is reading a low GPS number
> and the PCM thinks it's getting less air than it really is. Fuel trims
> and O2 live data would show that and changing the sensors will do nothing.
> Also you may wish to know that the only sensors involved with those
> codes are the two upstream sensors, the downstream units are for testing
> the cat efficiency and as back-ups to the upstreams if they fail.
>
It always amazes me how people think that a *code reader* is the be all
and end all of engine diagnostics. They seem to think an understanding
of what's going on under the hood is no longer necessary. Unfortunately
the diagnostician needs a very good understanding of system operation
else they will be continually replacing bits which are showing
*symptoms* of the real fault. This current case is the perfect example
of a little knowledge being a dangerous thing.

--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)