1. Home
  2. General Motors Forum
  3. Sonoma Service Engine Light -- How Long 'til It Clears?

Sonoma Service Engine Light -- How Long 'til It Clears?

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.

Reply to
catinthehat
Loading thread data ...

"catinthehat" wrote in news: snipped-for-privacy@l53g2000cwa.googlegroups.com:

i cant see how unhooking the battery is gonna clear an MIL on an OBD2 system.............maybe im just blind.

Reply to
Kjun

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.

Reply to
Woody

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..

Reply to
Woody

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?

Reply to
80 Knight

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.

Reply to
catinthehat

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.

Reply to
80 Knight

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.