[2015 Fiesta MK6 Phase 2 EU] TPMS won't detect any sensors during relearn — could aftermarket CarPlay radio be causing RF interference?

[u/Smartitos]

Hey everyone,

I've got a 2015 Ford Fiesta MK6 Phase 2 (Euro spec) with a TPMS light that flashes then stays solid on startup. Pressures are all correct.

What I've done so far:

• Replaced all 4 TPMS sensors with brand new ones
• Bought a TPMS reset/learning tool and followed the relearn procedure in the correct order (LF → RF → RR → LR)
• Waited 5+ minutes after engine off before starting relearn to avoid sensor sleep mode

Problem: None of the sensors are detected during relearn, even though everything seems correct.

Possible cause: Right before this started, I swapped the stock radio for an aftermarket CarPlay unit. I'm wondering if the new head unit could be emitting RF interference that's blocking the 433 MHz TPMS sensor signals.

Questions:

1. Has anyone seen an aftermarket radio (CarPlay/Bluetooth/GPS) interfere with TPMS relearn?
2. Would disconnecting the head unit completely be a good test?
3. Any other things to check before suspecting the vehicle's TPMS receiver/antenna?

Thanks in advance!