P0700Transmission Control System Malfunction
Get it checked soon
What it means
P0700 is a messenger, not the fault itself. The transmission control module detected a problem, stored its own code, and asked the engine computer to turn on the check-engine light. The actual detail lives in the transmission module — so the first job is reading codes from that module, which many basic scanners can't do.
Is it safe to drive?
Get it checked soon
The severity is whatever the underlying code says, so treat P0700 as find-out-fast. If the transmission is behaving — shifting smoothly, no slipping — have it read soon and don't panic. If it's slipping, banging into gear, or stuck in one gear (limp mode), stop treating it as check-soon and have it seen now; driving a slipping automatic destroys it quickly.
Common causes
Most likely first.
- Any fault inside the transmission control system — the specific TCM code names it
- Low or degraded transmission fluid
- Shift-solenoid or speed-sensor faults — P0715 is a common companion
- Wiring or connector damage between the TCM and the transmission
- Internal transmission wear
What the live data shows
This is the code where module coverage matters: a scanner that only queries the engine module shows P0700 and nothing else, while reading the transmission module surfaces the real fault code. Transmission fluid temperature — exposed on many cars — is worth a look too; overheated fluid alongside P0700 is its own answer.
A scanner that reads all 139 standard sensors shows you these readings live. ScanMyCar charts them as you drive, keeps the freeze-frame stored with the code, and pulls codes from every module — free, with any cheap Bluetooth adapter.
Typical fixes
Cheapest first, where honesty allows.
- Read the transmission module's own codes — the diagnosis starts there
- Check transmission fluid level and condition; dark or burnt fluid is a finding
- Repair wiring or connectors if the TCM code points at a circuit
- From there, follow the specific code — solenoid, sensor, or mechanical work
A guide, not a diagnosis. This page describes what P0700 generally means across OBD-II cars. What's actually wrong with your car depends on its live data and its history — and any repair decision deserves a proper diagnosis, whether that's you with a scanner or a professional with a lift.