P0700 — Transmission control system malfunction (request MIL)
A generic flag: the transmission controller logged a fault and asked the engine computer to turn on the check-engine light. The real clue is the companion transmission code.
What it means in plain English
P0700 is often a messenger code. It means the transmission control module (TCM) detected a problem and requested the malfunction indicator. You need the manufacturer-specific or detailed transmission codes stored with it. Fixating on P0700 alone leads nowhere.
Common causes
- Any TCM-detected fault (solenoids, sensors, ratio errors, wiring)
- Low or burnt transmission fluid (symptom, not always root)
- Communication issues between TCM and ECM
What you can safely check
- Use a scanner that reads transmission codes — many cheap tools only show P0700.
- Note shift quality, flares, harsh engagement, or limp mode.
- Check fluid level only with the procedure in your owner’s manual (some units are sealed).
Pull the code yourself (disclosed)
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A reusable Bluetooth OBD-II scanner lets you read the code and freeze-frame data before authorizing “mystery” diagnostics. One option: BlueDriver Bluetooth Pro OBD-II scan tool (BlueDriver/Levanta affiliate). Any capable OBD-II reader is fine — this is not required to use Fair Auto Shops.
When to go to a shop
Bring the car to a shop that can read TCM codes and do hydraulic/electrical diagnosis. Be skeptical of “rebuild the transmission” as the first quote without codes and tests — get a second opinion on major transmission work.
Typical related repair costs
We do not publish a single national average for “P0700 repair” because the code is not a part. Costs range from a sensor/solenoid job to a full rebuild depending on companion codes. Demand those codes on the paperwork.
Questions to ask before you authorize work
Use questions before you authorize a repair and how to read a repair estimate. Watch for patterns in spotting upselling.
Find an honest independent shop
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FAQ
Why does my cheap scanner only show P0700?
Many entry-level tools don’t query the TCM. You need a tool or shop that reads manufacturer transmission codes.
More check-engine codes
P0420 · P0430 · P0300 · P0301 · P0171 · P0174 · P0455 · P0456 · P0442 · P0446 · P0128 · P0401 · P0133 · P0113 · P0506 · P0507 · P0741 · P0011 · P0325 · P0340 · P0335 · P0101 · P0299 · P0135 · P0440 · P0441 · P0010 · P0500 · P0121
Hub: How to read a check-engine code · Repair cost guides · Affiliate disclosure