How do i reset limp mode on a 2002 deville or what would cause it to go into limp mode?

code p 0705 refers to transmission range (TR) sensor /switch--PRNDL input--circuit malfunction====causes --wiring---TR sensor /switch
replace the TR unt

Limp mode stops when the problem that caused it is repaired, which you have not done yet, whatever you did was not the problem that forced the vehicle into limp home mode keep doing the diagnostics and fix it right.

You have to find what is causing it to be in limp mode ! Have the vehicle checked for DTC's - diagnostic trouble codes . Do diagnostic's , fix what the problem is , sensor , wiring , a control module , then the light will go out .

Limp mode is triggered by a serious issue with the cars transmission or engine controls.

limp mode is when the ECM reduces power in the engine to prevent damage to the engine and gear box. It allows you to get the car to a position of safety to check items like oil and coolant levels and temperature .Run fault codes to find the cause of the limp mode

Most transmissions have a limp mode, or limp-home mode.
If the driveline computer thinks there is something wrong, it can lock the transmission into one gear, such as 2nd gear. Usually reverse will also be available. The Impala automatic has 4 speeds. 2nd speed or gear will get you home, but the engine rpms can get a little high. I wouldn't get on the expressway will in limp mode.
Before taking to the shop, you might want to try and reset limp mode by turning the car off for a couple minutes, or you may have to disconnect and reconnect the battery.

about a 100 different failures in the electronic control systems will cause this limp mode, have it tested by the dealer to determine the cause.

I'm guessing you overheated the engine, since that is what does it. Now if your temp is nowhere near 240 250 and it is stuck in it. Take it to a shop and have them reset the COMP

scan it.check vechicle speed sensor.a bad speed sensor will cause shift problems.

You will have to have the fault codes read and removed. If it is permanently in limp mode it may suggest another problem.