A check engine light appeared on my 2007 Mazda Cx-7 of 131000 miles. Then it developed a fault such that shifting the gear from Park to Drive position would make a noise and shake the car. Then once you start the vehicle it moves right to the third gear (shown on the dash board) and will not change again.

I sent it three mechanic shops including a Mazda dealer. Technically, the diagnosis did not show that it was transmission, but because it was difficult to shift the gear they all recommended that l should change the transmission and knock sensor which I did. However, the problem still persist when you start the vehicle in the morning or the engine becomes cold. Once you drive it for couple of minutes and stop and restart the engine, it will work perfectly. And the cycle keeps on. The engine light is still on and l sent it to Transmission expert and they could not detect the problem. Another shop checked the transmission control board and there was nothing wrong with it. Who is out there to help me?