How do you reset the ECU on a 97 nissan altima?

To reset the ECU on a 1997 Nissan Altima, disconnect the negative battery terminal and leave it off for about 15 minutes. This allows the ECU to clear any stored error codes. After 15 minutes, reconnect the negative battery terminal, and the ECU will reset. You may need to drive the car for a short period to allow the ECU to relearn the engine parameters.