AutoDiag

P0700

Transmission Control System (MIL Request)

Moderate· Fix soonIntermediatePowertrainGeneric, all makes

What it means

This code only tells you that the transmission computer (TCM) has stored its own fault code and asked the engine computer to turn on the check engine light. P0700 does not say what is wrong. You need a scan tool that can read the transmission module to see the real code.

Is it safe to drive?

Depends on the actual transmission code. If the car is shifting badly or stuck in one gear, drive gently.

Symptoms

  • Check engine light on
  • Possible harsh shifting or limp mode

Probable causes

Most likely first

  1. 1Any transmission fault stored in the TCM

How to diagnose it

Work through these in order before buying parts

  1. 1Use a scan tool that reads the transmission module (many basic code readers cannot) to get the specific transmission codes.
  2. 2Check the transmission fluid level and condition first (follow the maker's procedure; many need the engine running and the fluid hot). Dark, burnt-smelling fluid or metal debris points to internal wear.
  3. 3Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.

Common fixes

  • Repair the fault indicated by the transmission code

This information is general guidance for all makes. Exact causes, specifications and procedures vary by vehicle, so confirm with your service manual or a qualified mechanic before replacing parts.