Engine Code 12 '90 Suburban


Old 09-07-06, 06:36 AM
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Join Date: Mar 2006
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Engine Code 12 '90 Suburban

Does anyone know why a 1990 Chevy Suburban with a throttle body, not a carb, would throw a code 12? It has a 350 5.7L motor. Have searched many trouble code listings for this vehicle and none of them list a code 12. We have disconnected the battery and reconnected and it still throws out the code 12. The vehicle is clattering when accelerating. We cleaned the throttle body and replaced all the gaskets, still clattering. If you put the gas pedal too the floor, it will clatter and then the service engine light will come on. Once you turn the vehicle off and restart, the light stays off until you punch it again. Any help would be appreciated. Thanks!
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Old 09-07-06, 09:18 PM
the_tow_guy's Avatar
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Code 12 is the computer saying, "Hi, how you doing, I'm alive and doing fine". It normally appears at the beginning and end of the string of error codes.

Racking my brain because I had similar problem a while back (same engine, '94 vintage). I want to say it was either a knock sensor or knock sensor wiring, but don't quote me on that. Be a good idea to check the timing (if yours is like mine that will require disconnecting a one-wire plug in the ignition wiring) and replace the knock sensor; it's pretty cheap and easy to replace. Check the wire to the sensor very closely for bare spots. Replacement pigtail with connector is pretty cheap also.
Old 09-08-06, 07:27 AM
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Join Date: Mar 2006
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Thank you very much, The Tow Guy. I know on another car I had, that is what the code 12 was on it also, just wasn't sure on this vehicle. We will check out all the suggestions you gave and see if we can find the clattering. Again, Thank You!

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