how to fix the P0700 transmission control system malfunction in BMW 3 Series F30/F31 (2012-2019)

Solution

1. Preparation

• Gather tools: OBD-II scanner, multimeter, socket set, torque wrench, and any necessary replacement parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before starting work on transmission components.

2. Inspect and Replace Transmission Fluid

• Fluid Inspection

  • Remove the transmission dipstick or fill plug.
  • Check fluid level and condition; if fluid is low or burnt, proceed to replace it.

• Fluid Replacement

  • Lift the vehicle securely using jack stands.
  • Place a drain pan under the transmission pan.
  • Remove the transmission pan bolts using the socket set.
  • Carefully lower the pan to drain the old fluid.
  • Replace the transmission filter if applicable; remove the old filter and install the new one.
  • Clean the transmission pan and install a new gasket if necessary.
  • Reattach the pan and torque bolts to manufacturer's specification (typically around 10 Nm).
  • Refill the transmission with the recommended fluid type (check the owner’s manual for specifications).

3. Replace Transmission Control Module (if necessary)

• If diagnostics indicate a faulty TCM:
  • Disconnect the electrical connectors from the TCM.
  • Remove the mounting screws and take out the TCM.
  • Install the new TCM and secure it with screws.
  • Reconnect electrical connectors ensuring they click into place.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0700 and any related codes.
• Start the engine and allow it to idle for a few minutes.
• Take the vehicle for a test drive to ensure proper shifting and performance.