how to fix the P0700 transmission code on my BMW 3 Series G20/G21 (2019-2024)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety while working on electrical components.

2. Fluid Change

• Sub-steps:
  1. Locate the transmission fluid pan and drain plug.
  2. Place a drain pan beneath the transmission and remove the drain plug to drain old fluid.
  3. Replace the drain plug and tighten it to the manufacturer’s specifications (consult service manual for torque values).
  4. Remove the transmission fluid pan (if applicable) to access the filter, and replace the filter with a new one.
  5. Reinstall the fluid pan with a new gasket and tighten to specifications.

3. Wiring Inspection

• Sub-steps:
  1. Visually inspect the wiring harness connected to the transmission control module and transmission for frayed wires or poor connections.
  2. Clean any corrosion from the connectors using electrical contact cleaner.
  3. Repair or replace any damaged wiring or connectors as necessary.

4. TCM Testing

• Sub-steps:
  1. Reconnect the battery and use the multimeter to check the power and ground signals to the TCM.
  2. If power and ground are present, test the signal outputs to the transmission solenoids.
  3. Replace the TCM if it fails to provide correct output signals.

5. Solenoid Replacement (if necessary)

• Sub-steps:
  1. Locate the transmission solenoids based on the service manual.
  2. Disconnect the electrical connectors from the solenoids.
  3. Remove the solenoids from their mounting locations.
  4. Install the new solenoids and reconnect the electrical connectors.