Smart Fortwo MOST Bus Failure Kills All Media Systems

Experienced similar issues on a 2015 Smart Forfour. The MOST bus network completely failed, causing total multimedia blackout including audio system and navigation. The fiber optics ring was interrupted due to a faulty control unit. Diagnostic testing revealed multiple network communication errors across the automotive protocol chain. The main control unit needed replacement as it was no longer transmitting data through the fiber optic cables correctly. This is a serious issue requiring specialized equipment to diagnose and repair. The work involved removing several interior panels to access the affected components and reprogramming the new control unit to integrate with existing vehicle systems. The repair process took approximately 3 days due to parts availability and complex integration requirements. While this doesnt affect core vehicle operation, it completely disables all entertainment and navigation functions until fixed. Based on your symptoms, strongly suggest having a certified technician perform a full diagnostic of the MOST bus system. Look specifically for breaks in the fiber optic ring or failed control modules. These issues rarely resolve themselves and typically worsen over time.

Thanks for the detailed response! I had the same exact issue with my 2018 Smart Fortwo. The car diagnostics showed it was indeed a MOST bus system failure. After checking the entire bus network, they found the main module was faulty and disrupting data transmission. Would you mind sharing what the repair cost in your case? I paid 1200€ for the complete fix including parts and labor. Also curious if youve had any recurring issues since the repair? Mine has been working perfectly for 6 months now, but Im always watching for warning signs in the audio system.

Thanks for the update on your Smart Fortwo repair. In my case the total cost came to 1000€ for fixing the defective control unit in the MOST bus system. This included complete car diagnostics and reprogramming of the new module to ensure proper data transmission through the fiber optics network. Since the repair, my car electronics have worked flawlessly for over 2 years now. The audio system functions exactly as it should with no warning lights or error messages. The mechanic explained that once these control units are properly replaced and integrated, they rarely fail again. Great to hear your repair was successful too. The 1200€ you paid sounds reasonable considering the complexity of the MOST bus architecture and the specialized equipment needed to diagnose and repair these systems. Keeping an eye on the system is smart, but you probably wont see those issues return.

I took my Smart Fortwo to a certified shop last week after getting great advice here. The mechanic confirmed the MOST bus system failure through detailed car diagnostics. Their automotive protocol testing equipment pinpointed the exact control unit that was causing the communication breakdown. The repair process was actually smoother than expected. They had to remove several panels to access the car electronics and replace the faulty control unit. The entire job took 2 days and cost 1200€, which included parts, labor, and complete system reprogramming. The multimedia system is now working perfectly, radio, navigation, everything. Really relieved to have this fixed properly. The shop explained the bus system architecture and showed me the damaged components, which helped understand why the repair was necessary. Big thanks to everyone who helped identify the issue. Having knowledgeable techs diagnose and fix the problem was definitely worth the investment. Will update if any new issues pop up, but so far its running great after 6 months.