iPhone 15 Pro Max USB-C headphones recognized but no sound

If the iPhone is detecting the USB-C headphones but you’re getting no audio, that usually means the connection is working at a hardware level but audio is being routed somewhere else or the digital audio handshake is failing. Since you already ruled out debris, multiple headsets, and a restart, the next things to check are the audio output settings and system audio state.

• First, while the headphones are plugged in, open Control Center and press-and-hold the Now Playing card. Tap the AirPlay / audio output icon and confirm the output device is set to the USB-C headphones and not the iPhone speakers, Bluetooth device, or AirPlay destination. Also check Settings → Sounds & Haptics and make sure volume isn’t set to zero for media.

• If the routing looks correct, test whether any audio plays through them. Open Voice Memos or Music, start playback, and raise the volume with the side buttons while the headphones are connected. If the volume HUD appears but you still hear nothing, toggle Settings → Accessibility → Audio & Visual → Mono Audio on and off, and verify the Balance slider is centered.

Two other things you can try/check:

1. Try resetting your phone: Go to Settings → General → Transfer or Reset iPhone → Reset → Reset All Settings. This does not erase data but clears audio routing, USB configuration, and system preferences that sometimes get corrupted after updates.
2. Check to see that your phone is running the latest version of iOS: Go to Settings → General → Software Update. The latest currently (March 2026) is: 26.3.1

Finally, If the issue continues, the most likely causes are:

• A USB-C audio compatibility issue with that specific headset chipset or a partial USB-C port failure affecting digital audio lines (charging can still work normally).
• An iPhone USB port or logic board fault. Testing with an Apple USB-C to 3.5 mm adapter and standard headphones is a good diagnostic step. If that also produces no sound while still being recognized, it would point toward the port hardware and the phone should be inspected by Apple or an authorized service provider.