my BMW X3 F25 (2011-2018) transmission slips when hot what could be wrong

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, transmission fluid pump, multimeter, fluid catch pan, funnel.
• Ensure the vehicle is on a flat surface and elevate it using jack stands for safety.

2. Check and Replace Transmission Fluid

• Sub-steps:
  1. Start the engine and let it warm up to operating temperature.
  2. With the engine running, locate the transmission dipstick and remove it to check fluid level.
  3. If low, add the appropriate BMW transmission fluid (typically BMW ATF or equivalent), ensuring the correct type is used.
  4. If the fluid is contaminated or burnt, drain the old fluid using a fluid catch pan.
  5. Replace with fresh transmission fluid, ensuring to fill to the correct level.

3. Inspect and Replace Transmission Filter (if applicable)

• Sub-steps:
  1. Remove the transmission pan by loosening the bolts with a socket set.
  2. Carefully detach the pan and inspect the filter for blockage or damage.
  3. Replace the transmission filter if necessary.
  4. Clean the pan and reattach it with a new gasket, ensuring proper torque specifications are followed (typically around 8-10 Nm for pan bolts).

4. Test Transmission Components

• Sub-steps:
  1. Use a multimeter to test the resistance of the transmission solenoids according to the specifications in the service manual.
  2. Replace any solenoids that do not meet the required specifications.
  3. Reconnect any electrical connectors and ensure they are secure.

5. Final Assembly and Testing

• Sub-steps:
  1. Recheck the transmission fluid level and top off if necessary after all repairs.
  2. Start the vehicle and allow it to run, then conduct a road test to verify that the slipping issue has been resolved.