P0700: Transmission control system malfunction (see TCM codes)
The gearbox module has stored its own fault. Generic OBD-II only shows this summary code.
Updated
What P0700 means
Automatic gearboxes have their own control module. When it stores a fault, it asks the engine computer to turn on the check engine light, and the engine computer stores P0700.
P0700 itself doesn’t say what’s wrong: it points to the gearbox module, which holds the actual code.
Can I keep driving?
Check soon
Probably OK to drive short-term, but have it checked soon. Fuel use or emissions may be worse.
General guidance based on the code alone, not on the car’s actual condition. If in doubt, stop and ask a mechanic.
Many gearboxes switch to a limp mode when they have a fault, with harsh shifts or stuck in one gear. If the gearbox slips or won’t change gear, have it checked before driving far.
Symptoms
- Harsh, late or missing gear changes.
- The gearbox stays in one gear.
- On some cars, a gearbox warning on the dashboard.
Common causes
- Read the gearbox module with a brand-specific tool to see the actual fault. Read My Car reads every control unit that answers generic OBD2 requests, and on many cars that includes the gearbox, so its own code may be listed next to P0700 (“Reported by”). If it isn’t, a tool for your make can read it.
Typical fixes
- Read the codes and look for any reported by the gearbox module, next to P0700.
- Have the gearbox oil level and condition checked, as the service information for your gearbox describes.
- If no gearbox code shows, have the gearbox module read with a tool for your make.
Questions
Can I drive with P0700?
Gently, if the gearbox still shifts normally: the app’s advice is to have it checked soon. If it slips, won’t change gear or stays in one gear, have it checked before driving far.
Why does a generic scanner only show P0700?
Generic OBD2 reaches the engine and often the gearbox, but not every gearbox module shares its detailed codes that way. Then only the summary code P0700 shows, and the details need a tool for your make.