the check engine light and chck gas cap light is on because someone stole the gas cap, well i bought one from advanced auto parts but the lights r not going out. i was told to disconect the battery for 10 minutes but I'm not really sure what I'm doing...
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2007 Ford Focus
Question: disconecting battery
Answer #1dandd March 19, 2009, 09:36Master
Yes, just disconnect the NEGATIVE cable for the battery, with the key out of the ignition and all the doors closed. 5 minutes should more than do it. The negative cable is disconnected because all the circuit protection diodes in all the electronics are directed to ground. If you disconnect the positive and then hook that one back up, you could spike an electronic component and ruin it.
You may notice that the car will drive a little different and be hunting around with the idle speed for awhile. It may even start and die or stall at a few stops signs. This is because the computers need to re-learn their adaption settings which can take 10 miles or so.