Had a problem with the transmission of my Honda Civic EX Coupe '96. Returning from work, engine light turned on and transmission did not work. After few minutes parked at my place, transmission worked. Very next day on my way to
work, car ran good but with the light on. Transmission failed again in front of my place of work. Took the car to my regular shop. After some testing, they said a speed sensor and a solenoid need to be replaced so I authorized it. When car was done, 5 minutes on the expressway back home, light came on again but I felt the transmission smoother than ever. Went the following morning to the shop and they reset the light again. Drove to work and light DID NOT come on but returning home it did. Also noticed that it do not switch to third/fourth (not sure which one) gear. What could this be? What needs to be done?

Thanks in advance to help me figure out this situation.