how to fix CVT issues in BMW 3 Series E90/E91 (2005-2012) that overheats?

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, fluid pump, and transmission fluid.
• Ensure the vehicle is on a level surface and securely raised using jack stands.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Fluid Change

• Drain the existing transmission fluid:
  1. Remove the transmission drain plug using a socket set.
  2. Allow the fluid to completely drain into a catch pan.
• Replace the transmission filter:
  1. Remove the transmission pan by unscrewing the bolts with a socket set.
  2. Replace the old filter with a new one, ensuring proper alignment.
• Refill with new transmission fluid:
  1. Use a fluid pump to fill the transmission with the recommended CVT fluid (check owner’s manual for specifications).
  2. Check fluid level with the dipstick while the engine is running and the transmission is warm.

3. Cooling System Inspection

• Inspect the transmission cooler:
  1. Check for any blockages in the cooler and lines; clean as necessary.
  2. Replace any damaged lines or fittings.
• Ensure proper operation of the cooling fan:
  1. Test the fan by running the engine and monitoring for engagement when the temperature rises; replace if faulty.

4. Temperature Sensor Replacement (if necessary)

• Remove the transmission pan again if the temperature sensor is located within.
• Disconnect the old sensor and install the new one:
  1. Ensure the electrical connection is secure.
  2. Torque the sensor to the manufacturer's specifications.

5. Reassembly

• Reinstall the transmission pan and tighten the bolts to the specified torque.
• Reconnect the negative battery terminal.