P0700: Transmission Control System (MIL Request)
P0700 means Transmission Control System (MIL Request). The transmission control module (TCM) has stored a fault and is asking the engine computer to turn on the check engine light. P0700 itself does not say what the problem is.
P0700 only tells you that the transmission computer has a fault stored. The actual code lives in the transmission control module, so a scan tool that can read that module is needed.
Can I keep driving? Drivable with care. Diagnose soon: performance, economy or other components can be affected.
Common symptoms
- Check engine light on
- Possible harsh, delayed or missing shifts
- Possible limp mode (stuck in one gear)
Possible causes
- Any transmission fault stored in the TCM: sensor, solenoid, wiring or internal problem
How to diagnose P0700
- Read the transmission control module codes with a scan tool that can access it; generic code readers often only show P0700.
- Check transmission fluid level and condition.
- Diagnose the specific TCM code.
What the code means, digit by digit
Generic codes have the same definition on every OBD-II vehicle (petrol cars from model year 1996 in the US, 2001 in the EU; diesels later). Manufacturers can add their own enhanced codes; those are not listed here.
Symptoms linked to P0700
General guidance only. Fault codes describe what the engine computer saw, not which part failed: confirm with testing before replacing parts, and follow the vehicle's service information.