Possible reasons:
1. Mechanical faults:
* Defective shift cable or cable
* Worn or damaged shift plates in the transmission
* Shift lever sticking due to dirt or debris
2. Electrical faults:
* Faulty shift knob position sensor
* Short circuit or break in wiring
*Transmission control module (TCM) malfunction
3. Hydraulic faults:
*Low transmission fluid level
* Clogged or faulty oil filter
*Leak in hydraulic system
4. Other reasons:
*Broken or bent ignition key
* The brake pedal is not pressed when shifting from parking
Troubleshooting steps:
1. Check the transmission fluid level: Inspect the ATF dipstick and make sure the fluid level is between the marks. Add fluid if necessary.
2. Clean the shift lever: Remove any dirt or debris that may be preventing the shift lever from moving freely.
3. Check the position sensor: Check the shift position sensor for damage or contamination.
4. Check Wiring: Inspect wiring for corrosion, breaks or shorts.
5. Contact a mechanic: If you cannot determine the cause of the problem yourself, contact a qualified mechanic for further diagnosis and repair.