Why won't the 5-speed transmission go into gear?

the process involves plenty of hydraulic fluid as well as gears and clutches.
If you have an automatic transmission, and it "slips" while you are driving it-that is, the car engine revs without the power going to the wheels-the most common cause (though not the only possible cause) is low transmission fluid. If the slipping is caused by low fluid, it will get worse as the transmission gets hotter.

P0700 Transmission Control System

P0701 Transmission Control System Range/Performance

P0702 Transmission Control System -Electrical

P0703 Torque Converter/Brake Switch B Circuit

P0704 Clutch Pedal Position Switch -Circuit Malfunction

P0705 Transmission Range Sensor/Switch Circuit Malfunction (PRNDL Input)

P0706 Transmission Range Sensor/Switch Circuit Range/Performance

P0707 Transmission Range Sensor/Switch Circuit Low Input

P0708 Transmission Range Sensor/Switch Circuit High Input

P0709 Transmission Range Sensor/Switch Circuit intermittent

P0710 Transmission Fluid Temperature Sensor Circuit

P0711 Transmission Fluid Temperature Sensor Circuit Range/Performance

P0712 Transmission Fluid Temperature Sensor Circuit Low Input

P0713 Transmission Fluid Temperature Sensor Circuit High Input

P0714 Transmission Fluid Temperature Sensor Circuit Intermittent

P0715 Input/Turbine Speed Sensor Circuit

P0716 input/Turbine Speed Sensor Circuit Range/Performance

P0717 Input/Turbine Speed Sensor Circuit No Signal

P0718 Input/Turbine Speed Sensor Circuit Intermittent

P0719 Torque Converter/Brake Switch B Circuit Low

P0720 Output Shaft Speed Sensor Circuit

P0721 Output Shaft Speed Sensor Circuit Range/Performance

P0722 Output Shaft Speed Sensor Circuit No Signal

P0723 Output Shaft Speed Sensor Circuit Intermittent

P0724 Torque Converter/Brake Switch B Circuit High

P0725 Engine RPM Input Circuit

P0726 Engine RPM Input Circuit Range/Performance

P0727 Engine RPM Input Circuit No Signal

P0728 Engine RPM Input Circuit Intermittent

P0729 Gear 6 Incorrect Ratio

P0730 Incorrect Gear Ratio

P0731 Gear 1 Incorrect Ratio

P0732 Gear 2 Incorrect Ratio

P0733 Gear 3 Incorrect Ratio

P0734 Gear 4 Incorrect Ratio

P0735 Gear 5 Incorrect Ratio

P0736 Reverse Incorrect Ratio

P0737 TCM Engine Speed Output Circuit

P0738 TCM Engine Speed Output Circuit Low

P0739 TCM Engine Speed Output Circuit High

P0740 Torque Converter Clutch Solenoid Circuit

P0741 Torque Converter Clutch Solenoid Circuit Performance or Stuck Off

P0742 Torque Converter Clutch Solenoid Circuit Stuck On
P0743 Torque Converter Clutch Solenoid Circuit Electrical
Now i dont know a lot about automatics especially modern ones with all this fancy electronics thats used nowdays but i think its a fault with the temperature sensor for the gearbox.But where its located and what it looks like i have no idea it could even be mounted inside the gearbox .Sorry not a very good answer from a mechanic but?? very few of our europeon cars come with auto transmission .Evan when i do know whats wrong i cannot buy the parts for the gearbox as only re-con boxes supplied by the dealer so best advice is to try a specialist in auto box repairs only .PS some of my best students when i used to teach mechanics many moons ago were the girls so no excuses like iam only a girl please

Most possible ur transmission clutch r out.. if transmission fluid too low n u run it for sometimes the internal pump n the torque converter will damage too..

DTC P0736 - Reverse incorrect gear ratio

The clutch pressure control (PC) solenoid 2 flows fluid to the 3-5-R clutch when commanded OFF and exhausts fluid when commanded ON. The clutch PC solenoid 2 regulates the transmission fluid pressure to the 3-5-R clutch. The transmission fluid pressure (TFP) switch 1 Opens (High) under fluid pressure and closes (Low) when no pressure is present. The transmission control module (TCM) calculates gear ratio based on data from the automatic transmission input speed sensor (ISS) and the output speed sensor (OSS). The TCM compares the known transmission gear ratio to a calculated gear ratio for each commanded gear.

Circuit/System Verification:
Operate the vehicle to induce a shift from second to third gear while observing TFP Switch 1. Perform this action 2 times. The TFP Switch 1 should change states from Low to High. If the TFP Switch does not change states and no other DTCs set, replace the control solenoid (w/body and TCM) valve assembly. If any other DTCs set, diagnose that DTC first.
Operate the vehicle to obtain sixth gear 2 times and then check for DTCs other than DTC P0736.If any other DTCs set, diagnose that DTC first. If no other DTC sets, continue on with diagnostics.
Operate the vehicle by shifting from Park to Reverse, then while in reverse, operate the vehicle with the calculated throttle position greater than 8% for 5 seconds, perform this maneuver a minimum of 3 times. If the DTC P0736 resets, go to Component Testing.

Component Testing:
Perform the line test procedure.
Inspect the check ball 5 for possible sticking or damage. If you found a concern with this check ball, repair the concern.
Inspect the shift select valve 3 for sticking or damage. If you found a concern with the shift select valve 3, repair or replace the valve or valve body.
Inspect the R-1 (Low and Reverse clutch) assembly for wear or damage. If you found a R-1 assembly concern, repair or replace the R-1 assembly as necessary.

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day and Happy New Year.

DTC P0736 - Reverse incorrect gear ratio

The clutch pressure control (PC) solenoid 2 flows fluid to the 3-5-R clutch when commanded OFF and exhausts fluid when commanded ON. The clutch PC solenoid 2 regulates the transmission fluid pressure to the 3-5-R clutch. The transmission fluid pressure (TFP) switch 1 Opens (High) under fluid pressure and closes (Low) when no pressure is present. The transmission control module (TCM) calculates gear ratio based on data from the automatic transmission input speed sensor (ISS) and the output speed sensor (OSS). The TCM compares the known transmission gear ratio to a calculated gear ratio for each commanded gear.

Circuit/System Verification:
Operate the vehicle to induce a shift from second to third gear while observing TFP Switch 1. Perform this action 2 times. The TFP Switch 1 should change states from Low to High. If the TFP Switch does not change states and no other DTCs set, replace the control solenoid (w/body and TCM) valve assembly. If any other DTCs set, diagnose that DTC first.
Operate the vehicle to obtain sixth gear 2 times and then check for DTCs other than DTC P0736.If any other DTCs set, diagnose that DTC first. If no other DTC sets, continue on with diagnostics.
Operate the vehicle by shifting from Park to Reverse, then while in reverse, operate the vehicle with the calculated throttle position greater than 8% for 5 seconds, perform this maneuver a minimum of 3 times. If the DTC P0736 resets, go to Component Testing.

Component Testing:
Perform the line test procedure.
Inspect the check ball 5 for possible sticking or damage. If you found a concern with this check ball, repair the concern.
Inspect the shift select valve 3 for sticking or damage. If you found a concern with the shift select valve 3, repair or replace the valve or valve body.
Inspect the R-1 (Low and Reverse clutch) assembly for wear or damage. If you found a R-1 assembly concern, repair or replace the R-1 assembly as necessary.

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day and Happy New Year.

Hi Greg:
DTC P0736 - Reverse incorrect gear ratio

The clutch pressure control (PC) solenoid 2 flows fluid to the 3-5-R clutch when commanded OFF and exhausts fluid when commanded ON. The clutch PC solenoid 2 regulates the transmission fluid pressure to the 3-5-R clutch. The transmission fluid pressure (TFP) switch 1 Opens (High) under fluid pressure and closes (Low) when no pressure is present. The transmission control module (TCM) calculates gear ratio based on data from the automatic transmission input speed sensor (ISS) and the output speed sensor (OSS). The TCM compares the known transmission gear ratio to a calculated gear ratio for each commanded gear.

Circuit/System Verification:
Operate the vehicle to induce a shift from second to third gear while observing TFP Switch 1. Perform this action 2 times. The TFP Switch 1 should change states from Low to High. If the TFP Switch does not change states and no other DTCs set, replace the control solenoid (w/body and TCM) valve assembly. If any other DTCs set, diagnose that DTC first.
Operate the vehicle to obtain sixth gear 2 times and then check for DTCs other than DTC P0736.If any other DTCs set, diagnose that DTC first. If no other DTC sets, continue on with diagnostics.
Operate the vehicle by shifting from Park to Reverse, then while in reverse, operate the vehicle with the calculated throttle position greater than 8% for 5 seconds, perform this maneuver a minimum of 3 times. If the DTC P0736 resets, go to Component Testing.

Component Testing:
Perform the line test procedure.
Inspect the check ball 5 for possible sticking or damage. If you found a concern with this check ball, repair the concern.
Inspect the shift select valve 3 for sticking or damage. If you found a concern with the shift select valve 3, repair or replace the valve or valve body.
Inspect the R-1 (Low and Reverse clutch) assembly for wear or damage. If you found a R-1 assembly concern, repair or replace the R-1 assembly as necessary.

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day.

Check the hydraulic clutch fluid, if it is full then either the clutch is not releasing fully, the fluid inside the transmission is low, if the fluids are not low then the transmission will have to be replaced or rebuilt.

I assume its a manual transmission, sounds like the gears are whineing, check the fluid level, most manual are splash lubricated so low oil means not lubrication, also could be syncronizers, bearings, worn gears, out put/ in put shaft

pending on the type of clutch in the vehicle, you may be low on clutch fluid. (if your clutch is hydraulic)
other than that it is most likely the entire clutch itself.

Have them flush the fluid out under warranty and put in new fluid, and have them bleed the clutch lines in case air is getting in there. Audi and VW claim lifetime transmission fluid but it's BS - I've changed relatively low mile fluid from these cars and it was horrendous. It's possible that the fluid itself is causing trouble, but it's more likely that it is a synchro problem. If it was a clutch issue, you should have problems with more than just reverse gear - a clutch simply engages and disengages the engine and transmission, regardless of which gear it is. The problem (if not fixed by fluid) is in the transmission, and being under warranty, don't accept another "suggestion" like they're giving you. Changing your clutch isn't gonna do it.