your explanation is accurate, but the very thought of going back or going
to ANY dealer gives me cold shivers.
in my experiennce, i have never found a dealer interested in anything
but removing the dollars from the customer..
the disgusting charge for putting a car on the 'computer'
is robbery.
this corresponds to macing.
ten bucks for a diagnosis is reasonable. their prices are not.
the prices for repair and the parts are high enough to easily pay for
the 'computer'.
at this moment i have a dodge van with that code. i'll happily change
the O2 sensors one at a time and if no joy, i'll change the cat.
but no going to the dealer. the sensor cost is less that the computer test.
my best to all, sammmm
--
"Ray O" <rokigawaATtristarassociatesDOTcom> wrote in message
news:e8435$452e738a$44a4a10d$5774@msgid.meganewsservers.com...[color=blue]
>
> <wenmang@yahoo.com> wrote in message
> news:1160669044.902786.193420@i3g2000cwc.googlegroups.com...[color=green]
>> The scan tool I mean is the equipment to scan CAT system including O2
>> signals not the OBDII reader. I went to the local exhaust shop this
>> morning, they were not happy. They claimed that it was impossible for a
>> brand new CAT going bad within a month, there must have something wrong
>> with my car. They argued that there are a lot of factors which might
>> cause P0420 code set by the computer and they asked me to send my car
>> to dealer for check up, and they would not honor the warranty unless
>> dealer says it is bad(they were not convinced that CAT could be
>> defective). I am wondering whether there is other factor(s) that may
>> set P0420? I like to cancel the code and wait to see what will happen
>> next since it just passed the inspection and I have a year to find out.
>> I am wondering whether there may be false alarm for some unknown
>> reason. Anyway, it is very frustrated for me having to deal with P0420
>> code allover again.[/color]
>
> I personally prefer dealership service departments to avoid the very
> predicament you are facing. Toyota requires dealerships to have certain
> equipment, among them an exhaust gas analyzer, their technicians are
> factory-trained, and the warranty is backed up by the most financially
> secure car company in the world.
>
> The logic of how the ECM sets Diagnostic Trouble Code (DTC) P0420 is such
> that the most likely cause is a bad catalytic converter. #1 and #2 O2
> sensors work the same way and detect the presence of oxygen (O2) in the
> exhaust.
>
> Sensor #1 is sniffing the exhaust gas before it passes through the cat,
> and with the injectors sending fuel in pulses, the amount of O2 in the
> exhaust gas varies, so the voltage signal from Sensor #1 varies up and
> down.
>
> Sensor #2 sniffs the exhaust gas after it has passed through the cat, and
> the cat is supposed to clean up the gas. If the cat is working, the the
> voltage signal from sensor #2 should be much more even than the signal
> from sensor #1. If the signal from sensor #2 is varying and looks the
> same as the signal from sensor #1, then the cat has not changed the
> exhaust and the ECM sets DTC P0420.
>
> Other possible causes of P0420 are a damaged exhaust manifold or exhaust
> pipe (you would probably hear an exhaust leak), engine coolant temperature
> sensor not working properly, retarded spark timing, or bad O2 sensor.
>
> At this point, your best bet is to have a dealership diagnose the
> condition and with a written diagnosis, go back to the shop that did the
> work if something they replaced is bad.
> --
>
> Ray O
> (correct punctuation to reply)[color=green]
>>
>>
>> On Oct 12, 12:39 am, "Ray O" <rokigawaATtristarassociatesDOTcom>
>> wrote:[color=darkred]
>>> <wenm...@yahoo.com> wrote in
>>> messagenews:1160609005.854927.323010@m7g2000cwm.googlegroups.com...
>>>
>>> > Thanks Ray. I live in PA and I don't think that any place in US sells
>>> > leaded fuel
>>> > and I see no smoke coming out of exhaust pipe. The place where I have
>>> > CAT
>>> > replaced doesn't have scan tool. So I may have to send my car to other
>>> > place for the
>>> > scan in order to make sure that O2 sensors are good before exaust shop
>>> > can carry
>>> > out warranty otherwise, they probably won't do anything.No regular gas
>>> > stations sell leaded fuel, and
AFAIK, leaded fuel is not
>>> available in the U.S., but I like to cover all bases when I think of it
>>> ;-)
>>>
>>> No smoke out of the tail pipe is good!
>>>
>>> If the place that replaced the cat does not have a scan tool, then how
>>> did
>>> you get the code? If you have a personal scan tool, perhaps the shop
>>> that
>>> replaced the can use it to check the codes. You can chcek O2 sensor
>>> operation with a volt meter.
>>>
>>> If the cat is aftermarket, I'd bet that the replacement cat is bad.
>>>
>>> Good luck!
>>> --
>>>
>>> Ray O
>>> (correct punctuation to reply)
>>>
>>>
>>>
>>>
>>>
>>> > On Oct 11, 6:55 pm, "Ray O" <rokigawaATtristarassociatesDOTcom> wrote:
>>> >> <wenm...@yahoo.com> wrote in
>>> >> messagenews:1160599775.545655.124910@k70g2000cwa.googlegroups.com...
>>>
>>> >> > Hi,
>>>
>>> >> > It is raining today, on my way home, the check light turned on and
>>> >> > I
>>> >> > checked, it reads P0420. I just have CAT and 2 O2 sensors(front adn
>>> >> > back) replaced about a month, how come? what possibly went wrong?
>>> >> > What
>>> >> > should I do next?My guess would be that the replacement catalytic
>>> >> > converter is defective or
>>> >> something is contaminating the catalyst.
>>>
>>> >> Leaded fuel or huge amounts of engine oil leaking into the combustion
>>> >> chamber (with accompanying blue-gray clouds out the exhaust) could
>>> >> contaminate the catalyst, but if you don't see the blue-gray smoke
>>> >> and
>>> >> you
>>> >> haven't used leaded fuel, then a defective catalytic converter is
>>> >> likely.
>>>
>>> >> I would bring the car back to the place that installed the cat and
>>> >> sensors
>>> >> for a warranty repair.
>>>
>>> >> Good luck!
>>> >> --
>>>
>>> >> Ray O
>>> >> (correct punctuation to reply)- Hide quoted text -- Show quoted
>>> >> text -[/color]
>>[/color]
>
>[/color]
