CarPlay not working on iPhone while Android Auto works

How to recognise the problem

Android Auto works on the same unit and cable, but the iPhone does not start CarPlay. Owners report these presentations:

• The iPhone charges, but nothing appears on screen and no CarPlay prompt is shown.
• The unit shows 'USB device not supported', 'check mobile device' or 'Apple CarPlay is not supported on the mobile device'.
• The iPhone asks to be unlocked even though it already is.
• A CarPlay prompt or notification appears on the phone, but CarPlay never starts and the car does not show under CarPlay on the iPhone.
• The connection drops and reconnects repeatedly, or the charging indicator keeps cycling.
• The App-Connect or smartphone interface menu appears, but no device is listed.
• On some units the screen goes black when the iPhone connects.

Likely causes

The most frequently reported cause is the USB port. CarPlay needs an Apple-capable port, which contains the MFi authentication chip. Many VW Group ports only support Android Auto or plain media playback. Owners describe purple sockets as Android Auto only and green sockets as Apple/CarPlay capable.

Older ports without the E revision are reported as unsuitable; examples cited include 3Q0035846 and 3Q0035844B. Newer ports cited as CarPlay capable include 5Q0035726E and 5G0035222E. One explanation offered for the difference is that CarPlay needs the port to be externally powered, while Android Auto does not. This was suggested rather than confirmed.

On Audi MLB cars with MHI2Q, owners report that the VW module 5Q0035726E is not compatible and that the Audi part 8W0035736 is needed. 4M0035736 is cited as the MHI2Q-matching variant. Fitting a VW port in an Audi gave a smartphone menu but no phone recognition.

The second common cause is long coding byte 19 in address 5F. When it is set to USB 'Full', Apple mode is reported as disabled. Owners set it to iPod / usb_ipod, described as Apple plus Android.

Other reported causes:

• Activation not actually complete: the CarPlay FEC is missing or invalid, or the patch did not apply, even though the toolbox reported success.
• Adaptations not enabled: Apple_DIO, Google_GAL and Smartphone_interface_for_rhmi.
• A charge-only or poor-quality cable, including USB-C cables without data lines on newer iPhones.
• Siri disabled on the iPhone.
• The phone plugged into the wrong one of two ports, where only one (often in the armrest hub) supports CarPlay.
• A worn or partly damaged port that still charges.
• A USB stick left in another port interfering with detection.
• On an Audi TT, instrument cluster (cockpit) firmware not updated alongside the head unit.

Before changing coding or firmware

Several fixes below involve long coding, adaptations, re-patching or firmware updates. Before starting:

• Note the current software train and the head unit and USB port part numbers.
• Save a copy of the existing 5F long coding and adaptations so they can be restored.
• Keep a stable power supply connected to the car while coding or flashing.
• Do not flash firmware unless it matches your unit.

Fix: work through these steps in order

Owners resolved the problem at different stages, so check the cheap items first.

1. Rule out the cable and phone. Use an original Apple or OEM VW/Audi cable that carries data, not a charge-only cable. For USB-C iPhones, confirm the USB-C cable carries data. Clean the Lightning port. Unplug any USB stick from other ports. One owner's CarPlay appeared only after removing a stick.
2. Check iPhone settings. Enable Siri, including Listen for Hey Siri and Allow Siri When Locked, and allow CarPlay while locked. Under Settings > General > CarPlay, forget the car, then reconnect with the phone unlocked. Enabling Siri was confirmed as the fix in one case where the device list stayed empty.
3. Try the other USB port. Where the car has two ports, only one may be Apple-capable. Moving to the armrest or green port fixed it for some owners.
4. Check 5F long coding byte 19. With VCDS, OBDeleven or a similar tool, read byte 19 and change it from Full to iPod / usb_ipod. This was confirmed by several owners. Reports conflict, however: one owner who had only replaced the port with 5Q0035726E got 'not supported' on iPod and fixed it by setting Full. If one setting fails after a port change, test the other.
5. Check adaptations in 5F. Apple_DIO (CarPlay), Google_GAL (Android Auto) and Smartphone_interface_for_rhmi should be on. One owner left Mirror_link off because enabling it returned 'Value out of Range'.
6. Reboot after coding. Hold the power button about 15 seconds until the logo appears. On Audi MMI, owners rebooted by holding the menu button, the rotary control and the top-right button together. One owner fixed loss of detection after updating to K3663 this way.
7. Reset App-Connect or phone settings. Resetting App-Connect in the settings menu, rather than doing a full factory reset, was confirmed in one case. On MEN2, a factory reset through the menu restored a missing CarPlay option.
8. Verify activation. In the red engineering menu, check that the CarPlay FEC (0060800) and Android Auto FEC (0060900) are present and shown as valid or legal. If they are missing, the patch did not apply. Owners re-ran it, for example using the add FEC container option in patch_unit_aio. They also warned not to delete the addfec files from the patch folder, and to let the unit reboot by itself after patching (about 3-4 minutes was reported). One owner with valid FECs and working media playback was advised to restore original firmware and patch again.
9. Inspect or replace the USB port. Pop out the port, check its colour and part number, and look for damage. Replacing a faulty or Android-only port with a CarPlay-capable E-revision part is the most reported hardware fix. One owner confirmed CarPlay worked after replacing a partly damaged port. Fitting 5G0035222E on an older MIB2 car may also require a new cable loom, since the old wire lacks the extra side pins. On Audi MHI2Q, use the Audi part (8W0035736) with the original cable.
10. Audi TT and Virtual Cockpit cars. One owner on K1068/P5098 found CarPlay would not start from the connect button until the cockpit firmware was also updated. After that update, holding the steering-wheel voice button started CarPlay.

What did not help or gave mixed results

Factory resets alone often did not fix it when the port or coding was the cause. Several owners tried multiple resets with no change.

Swapping cables repeatedly did not help when the port itself was wrong or damaged. Wireless adapters such as Carlinkit also did nothing on cars whose port was not Apple-capable.

A software update alone is reported not to fix an Android-only port. One owner noted older USB hubs may not be supported after moving to 3342, which points to the hub rather than the update.

Replacing the port did not fix every case. One MST2_EU_VW_ZR_P0369T unit still had no CarPlay after a new port, and that case remained unresolved.

Some cases where Lightning iPhones fail but USB-C devices work, with charging cycling, also remain unresolved after resets and several cables.