Transmission control system (check TCM codes)
What P0700 means
Your car's computer set P0700: Transmission control system (check TCM codes). It belongs to the transmission group of codes. It is a generic code, so it means the same thing on every make. The check engine light usually comes on once the fault has been seen on two drives in a row. Until then it shows up as a pending code.
Can I keep driving? Get it checked soon. Transmission problems get expensive when ignored.
Common causes
- Low or old transmission fluid
- A transmission sensor or solenoid fault
- Transmission overheating from towing or heavy loads
Fix the cheapest, most likely cause first. Clearing the code without a repair only turns the light off until the fault comes back.
Check it yourself
Many transmission faults store more detail in the transmission module. A brand scan tool can read those.
Torque Deck reads P0700 with a cheap Bluetooth OBD2 adapter. It also shows the freeze frame (engine conditions at the moment the code set) and the live data you need to narrow it down.
Related codes
This page explains what the code usually means. It is not a diagnosis of your car. When in doubt, ask a mechanic.