2002 Renault Megane

Engine Mechanical problem
2002 Renault Megane 6 cyl Front Wheel Drive Automatic 40000 miles

The car seems to be sticking into the automatic version of 3rd gear. As soon I excellerate over 2500 revs after approx five minutes of driving there is a loud noise and the car jumps into the 3rd gear and will rev up to 3000 revs. It is happening more and more (most journeys). If I pull over and turn the engine off and restart the engine it will work perfectly fine again.
I have been told by an independant Renault dealer that it may be the soloid in the gear box?
Please help?
April 1, 2009.

The gearbox is controlled by the cars computer and should be showing a fault code if read by diagnostic computer .. it does sound like a sensor/actuator/solonoid may need replacing ..

Dave H
Apr 1, 2009.