I did reset the ECU on my 97 sentra gxe lst weekend. I am writing this to share my experience.
The engine check light came on after I start my engine without connecting the mass airflow sensor. It didn't go off even I reconnect the mass airflow sensor. I think it generated an error in ECU.
The solution is reset the ECU. Here is the right method.
It is a good article. The only thing that I want to mention here is that you need to do the screw method twice in a row to reset your ECU.
1.With the engine off, turn the ignition to the ON setting.
2. Turn the diagnostic mode selector on the back of the ECU fully clockwise.
3. Wait two seconds and turn the mode selector fully counter clockwise.
4. Turn the diagnostic mode selector on the back of the ECU fully clockwise.
5. Wait two seconds and turn the mode selector fully counter clockwise.
DO NOT turn on your engine between step 3 and step 4. That is the trick.
Btw, on my car, the disconnecting battery method didn't work well. I disconnected it for 4 to 5 hours while it didn't reset my ECU.
Hope this will help you. Thank you!