Asking for a litte, off topic help

I have to admit that this is not about the Miata, but this is one of the
better newsgroups for information. So I hope nobody minds that I ask.

We are considering buying a car that has the "check engine" light on.
Anticipating that this might be the case when I went to look at it, I
brought the handy code scanner with me.

The scanner said o420. The code description is "Catalyst System Efficiency
Below Threshold (Bank 1). What I have been able to determine, so far is that
either:

1. The downstream O2 sensor is misreading the output of the catalytic
converter or
2. The catalytic converter isn't doing it's job properly, which the O2
sensor is correctly reporting.

The car is a 2000 Mazda Protégé with about 115K miles on it. Thanks in
advance.

Ken

it could be the O2 sensor most times they do give reading i had it done
to me twice in my Mustang
at 115 i would not think its the Catalytic its still young and has lots of
time left lol

"KWS" > wrote in message
...
>I have to admit that this is not about the Miata, but this is one of the
> better newsgroups for information. So I hope nobody minds that I ask.
>
> We are considering buying a car that has the "check engine" light on.
> Anticipating that this might be the case when I went to look at it, I
> brought the handy code scanner with me.
>
> The scanner said o420. The code description is "Catalyst System Efficiency
> Below Threshold (Bank 1). What I have been able to determine, so far is
> that
> either:
>
> 1. The downstream O2 sensor is misreading the output of the catalytic
> converter or
> 2. The catalytic converter isn't doing it's job properly, which the O2
> sensor is correctly reporting.
>
> The car is a 2000 Mazda Protégé with about 115K miles on it. Thanks in
> advance.
>
> Ken
>
>

Thanks, Dale.

"Dale" > wrote in message
news:_rmLe.8145$vj.3330@pd7tw1no...
> it could be the O2 sensor most times they do give reading i had it
done
> to me twice in my Mustang
> at 115 i would not think its the Catalytic its still young and has lots
of
> time left lol
>
> "KWS" > wrote in message
> ...
> >I have to admit that this is not about the Miata, but this is one of the
> > better newsgroups for information. So I hope nobody minds that I ask.
> >
> > We are considering buying a car that has the "check engine" light on.
> > Anticipating that this might be the case when I went to look at it, I
> > brought the handy code scanner with me.
> >
> > The scanner said o420. The code description is "Catalyst System
Efficiency
> > Below Threshold (Bank 1). What I have been able to determine, so far is
> > that
> > either:
> >
> > 1. The downstream O2 sensor is misreading the output of the catalytic
> > converter or
> > 2. The catalytic converter isn't doing it's job properly, which the O2
> > sensor is correctly reporting.
> >
> > The car is a 2000 Mazda Protégé with about 115K miles on it. Thanks in
> > advance.
> >
> > Ken
> >
> >
>
>

Note however that various engine problems may have caused a premature
demise of the cat. I would take out the cat and check whether you
can see through it. If it is like the Miata, spray WD-40 onto the
bolts the day before.

Note that 4-wire O2 sensors are not that cheap, nor aftermarket
cats, at least for the Miata, that expensive.

Leon

"KWS" > wrote:

>Thanks, Dale.
>
>"Dale" > wrote in message
>news:_rmLe.8145$vj.3330@pd7tw1no...
>> it could be the O2 sensor most times they do give reading i had it
>done
>> to me twice in my Mustang
>> at 115 i would not think its the Catalytic its still young and has lots
>of
>> time left lol
>>
>> "KWS" > wrote in message
>> ...
>> >I have to admit that this is not about the Miata, but this is one of the
>> > better newsgroups for information. So I hope nobody minds that I ask.
>> >
>> > We are considering buying a car that has the "check engine" light on.
>> > Anticipating that this might be the case when I went to look at it, I
>> > brought the handy code scanner with me.
>> >
>> > The scanner said o420. The code description is "Catalyst System
>Efficiency
>> > Below Threshold (Bank 1). What I have been able to determine, so far is
>> > that
>> > either:
>> >
>> > 1. The downstream O2 sensor is misreading the output of the catalytic
>> > converter or
>> > 2. The catalytic converter isn't doing it's job properly, which the O2
>> > sensor is correctly reporting.
>> >
>> > The car is a 2000 Mazda Protégé with about 115K miles on it. Thanks in
>> > advance.
>> >
>> > Ken
>> >
>> >
>>
>>
>

--
Leon van Dommelen Bozo, the White 96 Sebring Miata .)
http://www.dommelen.net/miata
EXIT THE INTERSTATES (Jamie Jensen)

Thanks for the help, once again, Leon.

What I will likely do is (the easy thing, of course) simply change out the
downstream 02 sensor. The logic behind this is pretty much what I mentioned
in the original post. It might be simply reading good emissions incorrectly.
The general wisdom, which doesn't make it right....it's merely wisdom, is
that catalytic converters last a very, very long time.

If it works, the first stop is a local garage for an emissions check, as the
objective is to register this out of state vehicle in California. If that is
all successful and the light comes back on again at some later date, then
I'll look at something else.

Who knows? The crazy scheme might work.

Ken


"Leon van Dommelen" > wrote in message
...
>
> Note however that various engine problems may have caused a premature
> demise of the cat. I would take out the cat and check whether you
> can see through it. If it is like the Miata, spray WD-40 onto the
> bolts the day before.
>
> Note that 4-wire O2 sensors are not that cheap, nor aftermarket
> cats, at least for the Miata, that expensive.
>
> Leon
>
> "KWS" > wrote:
>
> >Thanks, Dale.
> >
> >"Dale" > wrote in message
> >news:_rmLe.8145$vj.3330@pd7tw1no...
> >> it could be the O2 sensor most times they do give reading i had it
> >done
> >> to me twice in my Mustang
> >> at 115 i would not think its the Catalytic its still young and has
lots
> >of
> >> time left lol
> >>
> >> "KWS" > wrote in message
> >> ...
> >> >I have to admit that this is not about the Miata, but this is one of
the
> >> > better newsgroups for information. So I hope nobody minds that I ask.
> >> >
> >> > We are considering buying a car that has the "check engine" light on.
> >> > Anticipating that this might be the case when I went to look at it, I
> >> > brought the handy code scanner with me.
> >> >
> >> > The scanner said o420. The code description is "Catalyst System
> >Efficiency
> >> > Below Threshold (Bank 1). What I have been able to determine, so far
is
> >> > that
> >> > either:
> >> >
> >> > 1. The downstream O2 sensor is misreading the output of the
catalytic
> >> > converter or
> >> > 2. The catalytic converter isn't doing it's job properly, which the
O2
> >> > sensor is correctly reporting.
> >> >
> >> > The car is a 2000 Mazda Protégé with about 115K miles on it. Thanks
in
> >> > advance.
> >> >
> >> > Ken
> >> >
> >> >
> >>
> >>
> >
>
> --
> Leon van Dommelen Bozo, the White 96 Sebring Miata .)
> http://www.dommelen.net/miata
> EXIT THE INTERSTATES (Jamie Jensen)

don't forget after you put the new one in to do a reset so the light will
go away after you put in the new OS

I just take the batt cable off for a few mins

"KWS" > wrote in message
...
>I have to admit that this is not about the Miata, but this is one of the
> better newsgroups for information. So I hope nobody minds that I ask.
>
> We are considering buying a car that has the "check engine" light on.
> Anticipating that this might be the case when I went to look at it, I
> brought the handy code scanner with me.
>
> The scanner said o420. The code description is "Catalyst System Efficiency
> Below Threshold (Bank 1). What I have been able to determine, so far is
> that
> either:
>
> 1. The downstream O2 sensor is misreading the output of the catalytic
> converter or
> 2. The catalytic converter isn't doing it's job properly, which the O2
> sensor is correctly reporting.
>
> The car is a 2000 Mazda Protégé with about 115K miles on it. Thanks in
> advance.
>
> Ken
>
>

Thanks, Dale.

Ken


"Dale" > wrote in message
newssJLe.217942$s54.84570@pd7tw2no...
> don't forget after you put the new one in to do a reset so the light will
> go away after you put in the new OS
>
> I just take the batt cable off for a few mins
>
> "KWS" > wrote in message
> ...
> >I have to admit that this is not about the Miata, but this is one of the
> > better newsgroups for information. So I hope nobody minds that I ask.
> >
> > We are considering buying a car that has the "check engine" light on.
> > Anticipating that this might be the case when I went to look at it, I
> > brought the handy code scanner with me.
> >
> > The scanner said o420. The code description is "Catalyst System
Efficiency
> > Below Threshold (Bank 1). What I have been able to determine, so far is
> > that
> > either:
> >
> > 1. The downstream O2 sensor is misreading the output of the catalytic
> > converter or
> > 2. The catalytic converter isn't doing it's job properly, which the O2
> > sensor is correctly reporting.
> >
> > The car is a 2000 Mazda Protégé with about 115K miles on it. Thanks in
> > advance.
> >
> > Ken
> >
> >
>
>