got a problem on my grand cherokee when selecting 1st or reverse it bangs into gear then as you drive it again it bangs into 2/3/4th gear with a bit of a thump, got an error code displayed of P 0700, and the check engine light is on,took it too Mtb chester jeep dealer for diagnosis, who informed me oil was low although i tended to disagree as i do check the oils frequently so they topped up the oil 2 litres ? they said and cleared the fault code drove it down the road i mean only 1/2 a mile it was still thumping into gear and the same error code re appeared took it straight back, mechanic cleared fault code and reprogrammed gearbox with factory settings, and said it would take the gearbox a while to "learn" / reprogram itself drove it 1/2 mile engine light came on again and the same error code P 0700 mechanic said try changing the speed sensors on the gearbox first before doing anything else, ........ anyone any ideas please