2024 BMW 3/4 Series Brake Fluid Tank Leak SIB 34 09 25

BMW has released Service Information Bulletin (SIB) 34 09 25 concerning a potential issue with the brake fluid expansion tank in various 2024 BMW models, including the 2024 BMW 430i. This service action aims to address a manufacturing defect that could lead to an internal leakage within the brake fluid expansion tank, also known as the brake fluid reservoir.

This bulletin, identified by NHTSA ID 11021109, outlines the necessary steps for dealers to inspect and repair affected vehicles. The repair is classified as both mobile-friendly and remote software upgrade (RSU) friendly.

Symptoms

Owners of affected vehicles may experience an internal leakage in the brake fluid expansion tank. In some cases, this leakage can lead to a malfunction of the filling level sensor over an extended period. While the document does not specify immediate driver-visible symptoms, a malfunctioning sensor could eventually lead to brake system warnings.

Cause

The root cause of this issue is identified as a manufacturing defect within the brake fluid expansion tank itself. This defect can compromise the integrity of the tank, leading to internal leakage.

Important Warnings for Technicians and Owners

BMW SIB 34 09 25 includes critical safety warnings, particularly regarding work on High-Voltage (HV) systems in BMW Group vehicles. These warnings are vital for ensuring technician safety and proper repair procedures:

• "Only properly trained personnel, who passed all applicable HV Technical Training Courses, should perform repairs which require disconnecting, or removal of High Voltage battery components on any Hybrid or Electric Vehicle. Work performed on High Voltage systems by unqualified persons may result in severe injury or damage to the vehicle. Additional safety information is found in Repair Instruction 61 00... 'Observe safety instructions when handling electric vehicles'."
• "Prior to disconnecting, or the removal of any HV component, the HV system needs to be disabled and secured (by means of the HV Service Disconnect Switch and lock out) by a properly trained HV technician, who has a minimum HV Qualification level after completing the Technical Training Course 'ST2324 High Voltage Drivetrain Systems' which as of 1/2023* includes ST1824 Alternative Drive Part 1."
• "Up to Generation 4 Vehicles once vehicle's HV system is disabled (the “Blitz" - lightning bolt icon is displayed in instrument cluster, see below), a technician without HV Certification may remove a HV component (e.g., EH Heater, EKK Compressor, EME Control Unit, et.), except for the High Voltage Battery."
• "For Generation 5 Vehicles however, the specific vehicle training is required to diagnose, remove and service any HV component and it is NOT allowed for non HV certified technicians to work on the high voltage system."
• "High Voltage Battery removal and rework can ONLY be performed by a High-voltage Certified Technician with a HV Battery Certification level corresponding to a specific Electric or Hybrid vehicle, for example: To repair GEN4 HV battery of G05 PHEV a certification from Technical Training Course 'ST2006 – SP44 HV Battery' or equivalent ST1825 – Alternative Drive Part 2 is required (or as of 1/2023 the equivalent 'ST 2325 for High Voltage Battery Systems'). And To repair A GEN5 HV battery the Technical Training Course 'ST2205 Generation 5 High-voltage class' is required or as of 1/2023* the equivalent 'ST 2325 for High Voltage Battery Systems'."

Repair Procedure Summary

The correction for the 2024 BMW 430i brake fluid expansion tank leak involves replacing the brake fluid expansion tank of the Integrated Brake system. Technicians are instructed to follow repair procedure REP 34 51 110, titled "Remove and install/replace expansion tank for integrated braking system." This procedure ensures the proper removal of the faulty tank and installation of a new one, restoring the integrity of the brake fluid system.

Required Tools or Parts

To perform the service action, specific parts and materials are required. These include:

• Expansion Tank: 34 51 9 504 021
• Hex Bolts:
  • 07 11 9 905 147 (M10x25-10.9ZNS3) - Quantity 4
  • 07 14 7 483 888 (M10x55 10.9 ZNS) - Quantity 4
  • 07 14 8 086 257 (M10x35) - Quantity 4
  • 07 14 5 B42 409 (M10x70) - Quantity 4
  • 07 14 9 502 134 (M10x1.5 ZNS3) - Quantity 2
  • 51 61 8 084 883 (M10x70) - Quantity 4 (for G87 models)
• Brake Fluid:
  • 81 22 0142156 (DOT 4, 12 oz bottle) - Sublet as needed
  • 81 22 0142155 (DOT 4, 1 Gallon) - Sublet as needed
  • 81 22 5B43922 (DOT 4, LV, 1/10-liter) - Sublet as needed
• Brake Parts Cleaner:
  • 83 19 5A53089 (Non-Chlorinated, 3% VOC, 15 oz) - Sublet as needed
  • 83 19 2451315 (Non-Chlorinated, 45% VOC, 15 oz) - Sublet as needed

The repair code for this service action is 0034200300, and it involves work packages such as 00 78 712 and 00 78 177 for renewing the brake fluid expansion tank. Additional work package 00 78 713 may apply for vehicles with fixed calipers and inaccessible rim designs.

Owner Action

If you own a 2024 BMW 3 Series or 4 Series model, including the 2024 BMW 430i, it is recommended to contact your authorized BMW dealer to determine if your vehicle is affected by Service Information Bulletin SIB 34 09 25. Dealers are instructed to perform this procedure on all affected vehicles before customer delivery or during the next service visit if the vehicle has already been delivered. This service action is performed free of charge under warranty.

Source: NHTSA ID: 11021109