how do you reset the brain so that the service engine light soon will go off

well,they told right and wrong!unhook the (negative) battery cable for a few minutes,then hook it back up.that will turn the check engine light off.but the computer stores that code in memory!so,if there is a problem,which there most likely is or the light would not have been on to start with,the light will come back on!if the person you got it from fixed the problem,and did not clear the light, it won't come back on.from what i understand in CA the parts houses are not allowed to read or clear your codes anymore.so if it comes back on you will need to find someone with a code reader to pull the codes for you,or buy one.

They lied. You need to have the monitors set before you can smog the car. The repairs must be made by the seller.

The monitors may need to be reset if the battery is disconnected. This sometimes can take over 100 hundred miles of drive time to set.