what is causing my BMW 3 Series G20/G21 (2019-2024) transmission to slip during shifts?

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety during electrical work.

2. Change Transmission Fluid and Filter

• Tools Required: Socket set, fluid pump, torque wrench, transmission fluid.
• Sub-steps:
  1. Raise the vehicle securely on jack stands.
  2. Locate the transmission pan and remove the bolts using a socket set.
  3. Carefully lower the transmission pan and allow the old fluid to drain into a suitable container.
  4. Remove the old filter and install a new transmission filter, ensuring it is seated properly.
  5. Clean the pan and replace the gasket with a new one.
  6. Reattach the transmission pan and torque the bolts to the manufacturer-specified value.

3. Inspect and Repair Electrical Connections

• Tools Required: Multimeter, wire brush.
• Sub-steps:
  1. Locate the transmission control module and inspect all wiring harnesses connected to it.
  2. Use a multimeter to check for continuity and proper voltage at the connectors.
  3. Clean any corroded connectors with a wire brush or contact cleaner.
  4. Replace any damaged wiring or connectors as needed.

4. Refill Transmission Fluid

• Tools Required: Fluid pump, funnel.
• Sub-steps:
  1. Using a fluid pump, refill the transmission with the appropriate type and amount of fluid as specified by the manufacturer.
  2. Start the engine and allow it to reach operating temperature, then cycle through all gear positions.
  3. With the engine running, check the fluid level using the dipstick and add more fluid if necessary.