The coolant vent lines of the low-temperature circuit are designed to remove air bubbles from the system...
BMW technical service bulletin B170126 for 2025 BMW 740I.
- Bulletin number
- B170126 (0017300200)
- Component
- Engine
- Summary
- The coolant vent lines of the low-temperature circuit are designed to remove air bubbles from the system toensure optimal cooling performance. Internal quality inspections have revealed that leaks may occur due tolocalized material aging on the vent lines. These leaks occur because the material originally used is notsufficiently resistant to the continuously high temperatures. A coolant leak may result and cause a yellow check control message and reduced engine performance.
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