Symptoms
- Transmission icon or 'check trans' message lit
- Possible harsh, delayed, or missed shifts
- Car may go into a limited 'limp' gear until restarted
Likely causes
- CommonLow or degraded transmission fluidLow fluid affects shift quality and can overheat the transmission.
- CommonFaulty transmission speed or temperature sensorSends bad data to the computer, which reacts defensively.
- PossibleTransmission overheating from towing or hard driving in heatEspecially relevant in hot climates or with a heavy load.
- PossibleInternal transmission wearMore serious and often follows a period of rough shifting before the light appears.
- Less commonWiring or connector issue at the transmissionLess common but possible, especially after other underbody work.
What to do
- Pull over safely if shifting feels harsh, delayed, or the car is stuck in one gear.
- Turn the car off, wait a minute, and restart to see if normal shifting returns.
- Check the transmission fluid level and condition if your vehicle has a dipstick (many modern cars don't).
- Avoid towing or hard acceleration until the issue is diagnosed.
- Have the code read at a shop to identify the specific sensor or fault.
- Get the fluid changed if it's low, burnt-smelling, or dark, along with the underlying issue addressed.
- Have a transmission specialist inspect further if the problem persists after fluid service.
Tools and parts
Transmission fluid, correct type for your carSearch: “transmission fluid type for your car make and model”
When to call a pro
See a transmission specialist promptly, since ignoring early warning signs can turn a fluid or sensor fix into an expensive rebuild.
Safety
Use caution
If the transmission is stuck in one gear or shifting harshly, avoid highway driving until it's checked; sudden gear changes can be dangerous in traffic.