P0700: Transmission Control System Malfunction
TL;DR
P0700 = the transmission control system has logged a fault (a notification code only). Severity: high. There is always a companion code (e.g., P0730, P0740, P0750…) that names the real issue — scan for it. Cost depends entirely on the underlying fault.
Can I keep driving with P0700?
IF the transmission shifts normally and there are no “limp mode” symptoms → drive cautiously to get it scanned. IF the transmission slips, won’t shift, or is stuck in one gear (limp mode) → drive minimally; continued driving can cause further transmission damage.
Symptoms
- Check engine light on
- Possible harsh, delayed or erratic shifting
- Transmission stuck in one gear (limp mode)
- Slipping
- Often no symptom beyond the light (depends on the real fault)
Top causes (ranked by probability)
| Likely cause | Probability | Notes |
|---|---|---|
| Underlying transmission fault named by a companion code | 80% | P0700 only flags it — read the other code(s) |
| Faulty solenoid, sensor or wiring in the transmission | 10% | |
| Low/old transmission fluid or TCM fault | 10% |
What does P0700 mean?
Technical explanation
P0700 is set by the powertrain control module when the transmission control module reports a fault that illuminates the MIL. It does not describe a specific failure; it is a flag that the TCM has stored one or more transmission DTCs. Proper diagnosis requires reading those companion codes (and often live transmission data) to identify the actual component or condition.
In simple terms
P0700 just means “the transmission computer found a problem and turned on the light.” It doesn’t say what the problem is — there’s always another code stored alongside it that tells you the real issue. You need a scanner to read that one.
How to diagnose P0700 (step by step)
- Scan for companion codes. This is essential — P0700 alone is not enough. Note every other P07xx or manufacturer transmission code.
- Check transmission fluid. Verify level and condition; low or burnt fluid causes many transmission codes.
- Research the companion code. Diagnose the specific code (e.g., solenoid, speed sensor, gear ratio).
- Inspect wiring/connectors. Check the transmission harness and connectors for damage.
- Test-drive with a scan tool. Watch live transmission data to confirm the fault.
Repair options & cost
- Diagnose and repair the companion code’s specific fault
- Replace a faulty solenoid or sensor
- Service/replace transmission fluid
- Repair wiring or, rarely, the TCM
| DIY cost | $0–$150 |
|---|---|
| Workshop cost | $100–$2,500 |
| Repair time | Varies widely by the underlying fault |
Costs are local ballpark ranges and vary by region and vehicle.
Tools you’ll need
- OBD-II scanner (BlueDriver / ANCEL)
- Transmission-capable scan tool
Vehicle-specific notes
- P0700 is generic across brands; the companion code is what matters.
- Always check fluid first — it is cheap and a common root cause.
- A full transmission-capable scanner (not just a basic reader) helps read TCM codes and data.
Common mistakes to avoid
- Trying to “fix P0700” directly instead of reading the companion code
- Ignoring transmission fluid level/condition
- Clearing the code without diagnosis
- Continuing to drive a slipping transmission
Frequently asked questions
What does P0700 mean exactly?
It means the transmission control module detected a fault and turned on the check engine light. It is a notification — a companion code stored with it identifies the actual problem.
Can I drive with a P0700 code?
It depends on the underlying fault. If shifting is normal, drive cautiously to get it scanned. If it slips or is in limp mode, minimize driving to avoid further damage.
How do I fix P0700?
You don’t fix P0700 directly — you scan for the companion transmission code, diagnose that, and repair the specific fault (often a solenoid, sensor, or fluid issue).
P0700 summary
| Meaning | Transmission control system fault (notification) |
|---|---|
| Severity | High |
| Safe to drive? | Depends on companion code / symptoms |
| Top cause | Underlying transmission fault (read companion code) |
| DIY cost | $0–$150 (diagnosis) |
| Shop cost | $100–$2,500 (varies) |