The cat converter on my 1999 2.2L Sonoma went to pieces internally:
lots of rattling, like broken glass rolling around in a can. At the
same time, a steady "Service Engine Soon" light came on. I got a new
cat installed this a.m. The Service Engine light is still on and I'm
wondering how long it will take the ECM to figure out the problem is
fixed and turn the light out? I've read anywhere from 4 to 50 starts
before it clears itself. I've also read you can clear it by
disconnecting the battery but have seen some cautions about doing
that. On some cars, apparently, if you clear the codes by
disconnecting the battery it will register some sort of "Unready"
status on the computer for a certain amount of time and, if you take
it in for smog test, it will fail due to that. I've got to smog this
truck by 1 March. Is that long enough for it to clear by itself ...
or for an "Unready" status to go away if I disconnect the battery?
Any advice appreciated.
It should have been cleared by the mechanic that did your converter. Ask
them if they can reset it. That is the only way you will know if it is
fixed. It could have destroyed the secondary O2 sensor. After reset it takes
three or four drive cycles for all the tests to complete which could take a
week or more depending on your driving. If you don't reset it or have the
car analyzed with an OBDII tester the light could stay on until it is
analyzed because of another problem.
In addition pulling the battery will reset the code and the tests also. Some
vehicles have tests such as idle learn that need run after disconnecting the
battery, You also may need radio codes if yours has them..
Take the truck to your local Autozone or similar, and get them to read the
codes for you. Some do it for free. If it is indeed related to the cat
converter, tell them to clear the codes with there OBD II scan tool. But, it
may not be a related code. Are you sure?
No I'm not sure but the timing of the event (cat falling apart) and
appearance of the Service Engine Soon light is extremely suggestive.
It could be just an amazing coincidence, however. Incidentally,
Autozones located in CA will no longer clear codes for anyone. They
say there is now a company policy against it. Autozone got sued by
somebody for something relating to clearing codes so they no longer
offer that service at any price.
Don't feel bad. I'm in Canada, and our Canadian Tire (the equivalent of the
USA's AutoZone) won't read (or clear) the codes for anything less then $80.
What about a local Napa or similar? I find they are much more customer
friendly. That's the problem with the OBDII system, though. You can't clear
the codes yourself, you need the scan tool. I went out to Wal Mart and got
one for around $120. I figured that equaled less then 2 trips to a shop to
tell me the code, and I can clear them as well.
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