When an automatic transmission will not shift, the cause is usually low or burnt fluid, a fault that has put the transmission into limp mode, an electrical problem such as a solenoid, speed sensor or range sensor, or internal wear. If it will not go into gear at all, also check the shift cable or linkage. Start with the fluid level and a code scan before assuming the worst.
Won’t shift vs won’t go into gear
| Symptom | Common causes |
|---|---|
| Stuck in one gear, often with a warning light | Limp mode from an electrical fault; see limp mode |
| Won’t shift out of first | Speed sensor or shift solenoid fault, low fluid |
| Won’t upshift until high RPM | Throttle position or governor pressure faults, low line pressure |
| Engine revs but no movement in any gear | Very low fluid, failed pump or converter, broken internal part |
| Selector moves but gear does not change | Broken or disconnected shift cable or linkage |
| Won’t come out of park | Brake-shift interlock or brake light switch fault |
Limp mode explains many “won’t shift” cases
When the computer sees a serious fault, it locks the transmission in one gear to protect it: many GM four-speeds such as the 4L60E start in third, and Chrysler RFE units sit in second. Codes such as P0700, P0715, P0750 or P0705 point to the cause; see 4L60E shift solenoids and 68RFE problems.
What to check, in order
- Fluid level and condition; see how to check transmission fluid and fluid color.
- Read codes with a scan tool that reads the transmission; see how to use an OBD2 scanner.
- Battery and charging voltage, since low voltage can trigger limp mode; see battery light on.
- The shift cable and range sensor; the selector position on the dash should match the lever; see transmission range sensor.
- Solenoids and wiring; see transmission solenoid symptoms.
Stuck in park
If the shifter will not leave park, the brake-shift interlock is usually the cause, often because the brake light switch has failed. Check whether the brake lights work. Most vehicles have a manual shift lock release slot near the shifter for emergencies; the owner manual shows where.
When it is internal
Burnt fluid, metal in the pan, slipping and ratio codes (P0730) mean internal damage; see transmission slipping and rebuild vs replacement, and find a replacement by code on our transmissions page.
More guides: car won’t move in drive · car won’t go into gear.
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