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May 30, 2025 Service bulletin

Complaint The following most common complaints may be observed: • Brief connectivity interruptions when...

Mercedes-Benz technical service bulletin LI82.85-P-079088 for 2020-2025 Mercedes-Benz C300, 2020-2025 Mercedes-Benz GLC 300 and 2020 Mercedes-Benz S550 and others.

Bulletin number
LI82.85-P-079088
Component
Electrical system
Summary
Complaint The following most common complaints may be observed: • Brief connectivity interruptions when using Apple CarPlay over Wi-Fi • Audio cuts out • Device not recognized • No operation possible Cause There are multiple possible causes for an iPhone disconnecting from a vehicle’s head unit while using Apple CarPlay. These include hardware, software, and environmental factors: Environmental Interference External Sources: • Passing under toll bridges, driving near airports, or areas with heavy electronic interference (e.g., as described in LI82.85-P-076157) can cause connection drops. Cellular Networks: • Interference from nearby cell towers operating on similar frequencies (usually 2.4GHz or 5GHz) can disrupt the signal. Storage Location: • Keeping your phone in a handbag or surrounded by other objects inside the vehicle can create physical or electronic interference. Device and Software Issues Head Unit Software/Hardware: • Outdated firmware, bugs, or hardware faults in the vehicle’s head unit can prevent a stable connection. iPhone Software/Hardware: • Similar issues in the iPhone, including buggy iOS updates or hardware problems, may affect performance. Reset or Reboot: • Automatic rebooting or resetting of either the head unit or the iPhone will temporarily disrupt CarPlay. Connection and Settings Wired Connections: • Faulty Cable: A damaged or poor-quality USB cable can cause intermittent or total loss of connection. • USB Port Issues: Dust, debris, or physical damage in the USB port of either the head unit or the iPhone can also lead to disconnects. Wireless Connections: • Intermittent Bluetooth/Wi-Fi: Unstable wireless communication (Bluetooth/Wi-Fi) can frequently break the Car- Play connection. Power Management: • Battery Saver Mode: Enabling low power mode may restrict background processes, affecting CarPlay. • Vehicle’s Electrical System: Unstable power delivery from the car’s battery or electrical interruptions can cause the head unit to malfunction. Phone & App Configuration Phone Settings: • Incorrect or conflicting settings (especially Bluetooth or Wi-Fi) on your iPhone can interfere with the CarPlay link. • Third-Party Apps/Profiles: • Installed apps or configuration profiles may conflict with CarPlay’s operation. • Native apps are apple maps, apple music, audio books, apple news, podcasts, messages and phone. All other apps are considered third party apps. App Conflicts: • Running conflicting apps that require similar system resources as CarPlay can cause instability. Mobile Data Plan: • Streaming from online sources without sufficient mobile data can result in lost connectivity. Other Factors Heat & Overheating: • If either the phone or the head unit overheats, they may disable certain functions to prevent damage, leading to disconnection. User Actions: • Accidentally disconnecting the device in settings, or physically moving or bumping the phone or cable, may disrupt the connection. Remedy Guided Diagnostic Path for Apple CarPlay Connection Issues Please follow the steps below to systematically diagnose and resolve CarPlay concerns: Update Devices: • Ensure the iPhone is updated to the latest available iOS version. • Ensure the vehicle’s head unit is updated to the latest software version available. Isolate the Issue: • Check whether the symptom persists with another iPhone running the latest iOS version. • Test both wireless and wired CarPlay connections: • Does the issue only occur with wireless CarPlay?

Owners of these vehicles have filed 166 complaints in the electrical category.

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