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Re: check engine light on in 97 wrangler YJ with error code reading 72

"bllsht" <nospam@dot.net> wrote in message
news:51j0r2lejqa7apj35s5jhrni154b3c4vq0@4ax.com...
>
>
>
> You're both leaping to conclusions without even having a clue as to
> how the PCM determines the cat converter's efficiency.
>

I'm not leaping to anything. If you would like to tell us how ti works, go
ahead. but, my guess is that it will boil down nicely to, "what comes out of
the CAT is not correct relative to what went in."

If what goes into the CAT is not correct, then there is a code that
specifies this condition. What comes out might not be correct, but if what
wen it was not correct first, that is the code to fix. If there is no code
addressing the condition of what goes into the CAT, but there is one that
addresses what comes out, I'll put my money on the sensor as the first and
foremost most likely suspect.

Re: check engine light on in 97 wrangler YJ with error code reading 72

"bllsht" <nospam@dot.net> wrote in message
news:nigrq2h2vlm58ducoftq5of5rvi6khcsp9@4ax.com...
>
>>
>>Having said all of that, the OP says he has a 97 YJ. In the 97, it was
>>called a TJ, and in 97, the codes are OBD II.
>
> A 1997 vehicle would be OBD II, no matter what it was called, or who
> made it.
>

Why are you dinging on me because the OP said he had a '97 YJ with OBD I?

I pointed out that the YJ was a TJ in '97, and in '97 they used OBD II.

Re: check engine light on in 97 wrangler YJ with error code reading 72

On Fri, 19 Jan 2007 05:11:08 GMT, "Jeff Strickland"
<crwlr@verizon.net> wrote:

>
>"bllsht" <nospam@dot.net> wrote in message
>news:51j0r2lejqa7apj35s5jhrni154b3c4vq0@4ax.com.. .
>>
>>
>>
>> You're both leaping to conclusions without even having a clue as to
>> how the PCM determines the cat converter's efficiency.
>>
>
>I'm not leaping to anything. If you would like to tell us how ti works, go
>ahead. but, my guess is that it will boil down nicely to, "what comes out of
>the CAT is not correct relative to what went in."
>
>If what goes into the CAT is not correct, then there is a code that
>specifies this condition. What comes out might not be correct, but if what
>wen it was not correct first, that is the code to fix. If there is no code
>addressing the condition of what goes into the CAT, but there is one that
>addresses what comes out, I'll put my money on the sensor as the first and
>foremost most likely suspect.
>
>
>

And you would be wrong again.

Re: check engine light on in 97 wrangler YJ with error code reading 72

On Fri, 19 Jan 2007 05:05:10 GMT, "Jeff Strickland"
<crwlr@verizon.net> wrote:

>
>"bllsht" <nospam@dot.net> wrote in message
>news:l9i0r25jnn68gvl1b940fdlkuelml6jh4f@4ax.com.. .
>> On Thu, 18 Jan 2007 19:01:19 GMT, "Jeff Strickland"
>> <crwlr@verizon.net> wrote:
>>
>>>
>>>"bllsht" <nospam@dot.net> wrote in message
>>>news:nigrq2h2vlm58ducoftq5of5rvi6khcsp9@4ax.com ...
>>>> On Tue, 16 Jan 2007 20:03:42 GMT, "Jeff Strickland"
>>>> <crwlr@verizon.net> wrote:
>>>>
>>>>>
>>>>>"bllsht" <nospam@dot.net> wrote in message
>>>>>news:567mq2lcmmf2td23fj2mo0bsfndgffg805@4ax.c om...
>>>>>> On Sun, 14 Jan 2007 14:41:18 -0600, "DougW"
>>>>>> <post.replies@invalid.address> wrote:
>>>>>>
>>>>>>>bspear78 wrote:
>>>>>>>> I have a check engine light on, and the code is reading a 12 and a
>>>>>>>> 72.
>>>>>>>> I know what the 12 means, but could not find any explanation for a
>>>>>>>> reading of 72. Anyone know what this means?
>>>>>>>
>>>>>>>72 Catalyst efficiency below required level. (Same as code 64)
>>>>>>>
>>>>>>>This means one of two things.
>>>>>>>1) your catalytic converter is plugging/cracking/failing
>>>>>>>2) the O2 sensor behind the cat is failing
>>>>>>
>>>>>> If the downstream O2 was failing you'd get a downstream O2 fault, not
>>>>>> a cat efficiency fault.
>>>>>>
>>>>>
>>>>>I'm not sure that is true in an OBD I car. The CAT is not a likely
>>>>>source
>>>>>of
>>>>>problems, and my money is on the after-CAT sensor going bad.
>>>>
>>>> An OBD I jeep wouldn't even have a downstream O2 sensor. You just lost
>>>> your money.
>>>>
>>>>>
>>>>>I am pretty sure that the downstream sensor can give an error that says
>>>>>the
>>>>>CAT is failing. This can happen because the system doesn't know that the
>>>>>sensor is bad, it only knows that the input from the sensor is not
>>>>>correct.
>>>>>The sensor can fail in a mode that makes the system say that the CAT is
>>>>>not
>>>>>working when the reality is that the sensor itself has taken a bye.
>>>>
>>>> Wrong. A failed downstream sensor will not set a cat efficiency fault.
>>>> In fact, the poorer the downstream sensor functions, the less likely a
>>>> cat fault would result.
>>>>
>>>>>
>>>>>Having said all of that, the OP says he has a 97 YJ. In the 97, it was
>>>>>called a TJ, and in 97, the codes are OBD II.
>>>>
>>>> A 1997 vehicle would be OBD II, no matter what it was called, or who
>>>> made it.
>>>>
>>>
>>>Well, then we're all chasing our shadows. Because, an OBD II car won't
>>>have
>>>a Code 72 ...
>>
>> Oh really? Please tell us how you came to that conclusion.
>>
>
>Which conclusion?

Your conclusion that an OBD II 1997 Jeep wouldn't flash a code 72.

>
>OBD II specs say that the code will be something like P0440, where there is
>an alpha digit followed by 4 numeric digits. 72 does not fit the spec.

1997 Jeeps don't flash OBD II codes. They flash 2 digit numbers using
the check engine light. If you scan one with an OBD II scanner, you
will, however, get an OBD II code.

>
>Would you like the link to the OBD II spec?

That won't be necessary. Please keep impressing us with your lack of
OBD II and 1997 Jeep knowledge?

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