casca

ok, replaced o2 sensor after checking codes, got 12 & 21
had to disconnect battery to clear code 21 even after replacing o2 sensor.
with in 24 hours the check engine light pops back on. damn same codes again
12 & 21.
so we have a new o2 sensor in place? so disconnect battery again just on a
whim and code 21 is cleared??

any Ideas?? bad battery ?? charge indicator shows 14volts if gauge is
close. no problem with dim light---- no problem with starting-
only problem I have is check engine light comes on?

could voltage regulator be going out ??

in the dark with no flashlight - ya gotta lead me by hand!!
thanks

Jerry Bransford

Which 02 sensor did you replace? There are at least two 02 sensors on early
TJs and from what I hear and read, four 02 sensors on the latest TJs.

Jerry
--
Jerry Bransford
KC6TAY, PP-ASEL
See the Geezer Jeep at
http://members.***.net/jerrypb/

"casca" <casca@megsinet.net> wrote in message
news:vjgui6arnj6472@corp.supernews.com...
> ok, replaced o2 sensor after checking codes, got 12 & 21
> had to disconnect battery to clear code 21 even after replacing o2 sensor.
> with in 24 hours the check engine light pops back on. damn same codes
again
> 12 & 21.
> so we have a new o2 sensor in place? so disconnect battery again just on a
> whim and code 21 is cleared??
>
> any Ideas?? bad battery ?? charge indicator shows 14volts if gauge is
> close. no problem with dim light---- no problem with starting-
> only problem I have is check engine light comes on?
>
> could voltage regulator be going out ??
>
> in the dark with no flashlight - ya gotta lead me by hand!!
> thanks
>
>

casca

only one that I was aware of was one down on exhaust before cat. converter.
did not see any others mentioned in any manuals or at auto parts stores ?
thanks
"casca" <casca@megsinet.net> wrote in message
news:vjgui6arnj6472@corp.supernews.com...
> ok, replaced o2 sensor after checking codes, got 12 & 21
> had to disconnect battery to clear code 21 even after replacing o2 sensor.
> with in 24 hours the check engine light pops back on. damn same codes
again
> 12 & 21.
> so we have a new o2 sensor in place? so disconnect battery again just on a
> whim and code 21 is cleared??
>
> any Ideas?? bad battery ?? charge indicator shows 14volts if gauge is
> close. no problem with dim light---- no problem with starting-
> only problem I have is check engine light comes on?
>
> could voltage regulator be going out ??
>
> in the dark with no flashlight - ya gotta lead me by hand!!
> thanks
>
>

David C. Moller

What Jerry said... the 21 can indicate either the upstream or the
downstream O2 sensor.

Dave
http://home1.gte.net/res0p2es/david/index.htm

On Mon, 11 Aug 2003 23:01:32 -0700, "Jerry Bransford"
<jerrypb@***.net> wrote:

>You've replaced the "downstream" 02 sensor. The 02 sensor that normally
>triggers the code is the "upstream" 02 sensor just below the exhaust
>manifold.
>
>Jerry

L.W.(=?iso-8859-1?Q?=DFill?=) Hughes III

http://www.----------.com/O2sensors.jpg
God Bless America, ßill O|||||||O
mailto:--------------------

casca wrote:
>
> only one that I was aware of was one down on exhaust before cat. converter.
> did not see any others mentioned in any manuals or at auto parts stores ?
> thanks

casca

tell me more , where can I find more info & or picture??

"David C. Moller" <david_moller@msn.com> wrote in message
news:h61hjvk0jh5hk6p0khnealimf19ikei8tr@4ax.com...
> What Jerry said... the 21 can indicate either the upstream or the
> downstream O2 sensor.
>
> Dave
> http://home1.gte.net/res0p2es/david/index.htm
>
> On Mon, 11 Aug 2003 23:01:32 -0700, "Jerry Bransford"
> <jerrypb@***.net> wrote:
>
> >You've replaced the "downstream" 02 sensor. The 02 sensor that normally
> >triggers the code is the "upstream" 02 sensor just below the exhaust
> >manifold.
> >
> >Jerry
>

casca

well in for a penny in for a pound ?? guess will have to change rear sensor
"I thought" ( that's where the problem usually starts)
that there was only one-- at one end or the other !! so will go check and
switch the other. At 79000 miles probably about due??
just can't figure out why code clears temporary after battery disconnected
or does it just take awhile for it to get a good reading??
think I can get away driving it for a few days , until I can get under it??
thanx
"Carlo Jr." <carlo.jr@comcast.net> wrote in message
news:7k0_a.125140$o%2.54924@sccrnsc02...
> He said that he replaced the one before the cat - could be that the O2
> sensor is properly sensing exhaust that is not within normal limits - or
as
> mentioned, it could be the downstream sensor malfunctioning or telling us
> that the cat is not performing ??????
> Someone with a Snap-On MT2500 could see which one is doing what........
>
> --
> Carlo F. Serusa, Jr. RPh
> carlo.jr@comcast.net
> '98 Sahara TJ - '89 YJ - '79 Scout II
> O|||||||O
> '92 Explorer '65 Mustang
>
>
> "L.W. (ßill) ------ III" <----------@***.net> wrote in message
> news:3F38889B.C1AB946@***.net...
> > http://www.----------.com/O2sensors.jpg
> > God Bless America, ßill O|||||||O
> > mailto:--------------------
> >
> > casca wrote:
> > >
> > > only one that I was aware of was one down on exhaust before cat.
> converter.
> > > did not see any others mentioned in any manuals or at auto parts
stores
> ?
> > > thanks
>
>

David C. Moller

I believe they (upstream/downstream) are interchangeable (may be wrong
though). I'd probably replace both for the heck of it, but if you
wanted to, you could probably try the new one in the other location,
and put an 'old' one back where you had the new one.
Disconnecting the battery will clear all codes (except battery
disconnect code), so it makes sense that everything is fine until it
senses the O2 malfunction again IMO.
From what I know, you're fine driving for a while if it's an O2 sensor
failure. It's strictly an emissions thing... won't hurt the vehicle.

Dave
http://home1.gte.net/res0p2es/david/index.htm

On Tue, 12 Aug 2003 02:22:05 -0500, "casca" <casca@megsinet.net>
wrote:

>well in for a penny in for a pound ?? guess will have to change rear sensor
>"I thought" ( that's where the problem usually starts)
>that there was only one-- at one end or the other !! so will go check and
>switch the other. At 79000 miles probably about due??
>just can't figure out why code clears temporary after battery disconnected
>or does it just take awhile for it to get a good reading??
>think I can get away driving it for a few days , until I can get under it??
>thanx
>"Carlo Jr." <carlo.jr@comcast.net> wrote in message
>news:7k0_a.125140$o%2.54924@sccrnsc02...
>> He said that he replaced the one before the cat - could be that the O2
>> sensor is properly sensing exhaust that is not within normal limits - or
>as
>> mentioned, it could be the downstream sensor malfunctioning or telling us
>> that the cat is not performing ??????
>> Someone with a Snap-On MT2500 could see which one is doing what........
>>
>> --
>> Carlo F. Serusa, Jr. RPh
>> carlo.jr@comcast.net
>> '98 Sahara TJ - '89 YJ - '79 Scout II
>> O|||||||O
>> '92 Explorer '65 Mustang
>>
>>
>> "L.W. (ßill) ------ III" <----------@***.net> wrote in message
>> news:3F38889B.C1AB946@***.net...
>> > http://www.----------.com/O2sensors.jpg
>> > God Bless America, ßill O|||||||O
>> > mailto:--------------------
>> >
>> > casca wrote:
>> > >
>> > > only one that I was aware of was one down on exhaust before cat.
>> converter.
>> > > did not see any others mentioned in any manuals or at auto parts
>stores
>> ?
>> > > thanks
>>
>>
>

Peter Parker

In article <8n5hjv48c8db5cf32725psht5mm5ji8gah@4ax.com>,
David C. Moller <david_moller@msn.com> wrote:
>I believe they (upstream/downstream) are interchangeable (may be wrong
>though). I'd probably replace both for the heck of it, but if you
>wanted to, you could probably try the new one in the other location,
>and put an 'old' one back where you had the new one.
>Disconnecting the battery will clear all codes (except battery
>disconnect code), so it makes sense that everything is fine until it
>senses the O2 malfunction again IMO.
>From what I know, you're fine driving for a while if it's an O2 sensor
>failure. It's strictly an emissions thing... won't hurt the vehicle.

Only that you will get $hitty gas mileage and will be running inefficient.
I would suspect a bad wire at one of the O2 sensor connectors. Intermittant.
Pull on the wires or use a volt meter to determine a proper connection.


--
<html><form><input type crash></form></html>
nospam@zero.com Replace nospam with jetta to reply via e-mail

Carlo Jr.

I say again.............find someone with a scanner that has data stream -
that way you can determine if it is a sensor or if it is what it is
sensing..............

--
Carlo F. Serusa, Jr. RPh
carlo.jr@comcast.net
'98 Sahara TJ - '89 YJ - '79 Scout II
O|||||||O
'92 Explorer '65 Mustang


"Peter Parker" <nospam@zero.com> wrote in message
news:3f3901ce_2@nntp2.nac.net...
> In article <8n5hjv48c8db5cf32725psht5mm5ji8gah@4ax.com>,
> David C. Moller <david_moller@msn.com> wrote:
> >I believe they (upstream/downstream) are interchangeable (may be wrong
> >though). I'd probably replace both for the heck of it, but if you
> >wanted to, you could probably try the new one in the other location,
> >and put an 'old' one back where you had the new one.
> >Disconnecting the battery will clear all codes (except battery
> >disconnect code), so it makes sense that everything is fine until it
> >senses the O2 malfunction again IMO.
> >From what I know, you're fine driving for a while if it's an O2 sensor
> >failure. It's strictly an emissions thing... won't hurt the vehicle.
>
> Only that you will get $hitty gas mileage and will be running inefficient.
> I would suspect a bad wire at one of the O2 sensor connectors.
Intermittant.
> Pull on the wires or use a volt meter to determine a proper connection.
>
>
> --
> <html><form><input type crash></form></html>
> nospam@zero.com Replace nospam with jetta to reply via e-mail