I have a 2007 volvo s40 2.4, anytime that the car reaches speeds above 50 to 60 the transmission service urgent light comes on and the only gears i have are 2nd and 4th. When i turn the car off and restart it its fine for a little bit but does it again. what could this be? They have already replaced the transmission and torque converter, tcm, shifting solenoid and lockup sensor.

 

If you can, test the sensors that feed info to the transmission (speed, temp, ABS wheel sensors, etc.). I do not know them all. Different transmissions are set up somewhat differently and I don't know about the s40's setup. What I do know is that across different car lines with automatic transmissions nowadays use a bunch of sensors and most power train computers are set to throw the car into one or another sort of "limp mode" if sensor data is confusing or corrupt. Or if the computer that controls the power train develops a fault.

What one has to do is connect a scan tool to the car that will read the live data stream from the sensors of interest, then take a drive until the problem recurs. Back at the garage then it's just a matter of reading the data log to see which sensor goes out of range when. If the sensors are feeding good data then the fault may be in the power train computer; in troubleshoooting one would replace it with a known good (not necessarily new) unit and run the test again.

You'd be surprised at the variety of things that can give rise to this kind of problem, including in some cases jump-starting or unrelated work on the car in the vicinity of a sensor or its connector.

 

Ill talk to the shop that has my car and let them know. its getting so frustrating. the mechanic has literally told me they are just guessing because they have no clue whats wrong with it.

 

Your B4 brake band could be worn past specification.
Test by removing the B4 solenoid and checking for excessive travel. My 2001 V70 T5 has had similar problems and failed to adequately brake the shaft while shifting between 2nd and 3rd gears. After long enough, the overrunning shaft can wear the gear clutch packs out and they will need replacement and a rebuild.

if lucky, you can drop the driver’s side subframe to remove the cover and change out the B4 band. This will fix the 2-3 flare along with ensuring that the operation and condition of its solenoid is not abnormal or it is not binding.

 

If you have fixed the problem... Please let me know what was it?