Renault megane stops changing gear during drive

hey guys, thanks so much for your help. So my 2002 Renault with only 70000 (km) in the speedometer, stops changing gear in the middle of the drive and doesn’t go higher than the first gear (it’s automatic). My mechanic did a restart for the computer 2 months ago and it was Ok until 2 days ago. What do you think should be done?
Thanks so much, Gili

Most likely, the computer is losing an input from a critical sensor like the Vehicle Speed Sensor; Throttle Position Sensor: Mass Air Flow sensor; etc. When this happens the computer goes to a safe mode which is called ‘limp home’ mode i.e. one useable gear and full pump pressure is commanded. If your mechanic has the ability to pull trouble codes from the transmission computer (aka power management computer) that might lead him/her to the likely faulty component or circuit.

If this were my car, I would run it by the manufacturer’s or dealer service department. They usually have the trained technicians, tools and software to analyze the problem.

Hope this helps.

Thanks a lot, I’ll try to go to the manufacture service.