Model Year 20/21 Tailgate problems and random Airbag fault

[Sidemine]

Hi, I’m trying my luck here and asking if anyone has experience with the Cupra Formentor 2.0 VZ 310 hp AWD, model year 2021.


The issue is that every few weeks or months, an airbag fault warning light appears on the dashboard. So far, the problem has usually gone away after turning the car off, locking it, and then unlocking it again.


Yesterday, a reverse assist fault appeared again after a long time, but it disappeared once I restarted the car.


Another issue concerns the tailgate. When using the car’s controls (e.g. the remote key) in a certain sequence, the tailgate lock seems to go into a fault mode. Typically, the issue occurs if I first unlock the car with the remote, then open the tailgate with the remote, and then get into the car. Even if I close the tailgate using its close button, it goes all the way down, but the hazard lights flash four times and the tailgate does not lock. Physically, the tailgate is closed, but the car’s display shows it as open.


Usually, fixing this requires turning the car off, locking and unlocking it again, and then closing the tailgate once more (even from the inside using the tailgate button), after which it locks properly.


When this fault is active, pressing the tailgate close button only produces a creaking sound (when the tailgate is open), and it may move just a few centimeters up or down. If I try to push the tailgate closed manually, it starts to close, but after a couple of seconds it opens slightly again on its own.


The car has already had the tailgate locking mechanism, the J605 control unit, and the suction assist motor replaced (the motor that pulls the tailgate fully shut). However, for example, the BCM module has not been replaced, which I have considered, or there could be a wiring harness issue.


What could be causing this? Does anyone have similar experiences?


Thanks a lot in advance for your help.

 

[dbbloke]

Hi, I have a 2023 Cupra Formentor VZ3 310hp AWD with very similar issues — random faults that clear on restart, present since delivery at 270km - 47k car!!

My primary fault codes (present from new, documented in OBDeleven scan at 270km):

• B1802F1 — NV Energy management alarm
• U105000 — Battery monitoring control module no communication

Do you have the above?

Cascading faults that come and go (usually go after dealer clearing and charge battery or the unlearning counter gets to 0):

• U14E400 / U010100 — TCM transmission comms loss
• C1187F6 — Brake booster functional limitation
• P060C00 — Engine ECU internal processor performance
• U112300 — Data bus error value received (multiple modules)
• U105400 — Infotainment comms loss (several variants, unlearning going up)
• B184C00 — BCM activation
• P14AC00 — Exhaust flap
• B105411 — GPS antenna short circuit

Symptoms throughout ownership include: boot opening partially (foot sensor), car unlocking itself or locking me inside, heated seats turning on by themselves, reversing camera unavailable, kickdown hesitation/selecting neutral at 45mph, cruise control dropping out, Travel Assist unavailable, SOS Emergency Call unavailable. No to mention DCC seemingly off/on, at least A/C soleniod started working

Recently On 13 June 2026 cruise control, Travel Assist and SOS all failed simultaneously while driving — had to turn home. Timestamped diagnostic scan confirmed the cascade across multiple modules at exactly the same second, 10 modules went offline until restart!

Battery has been confirmed healthy multiple times on VAS 6161. Cupra cited TPI 2060677/4 saying no customer claim possible as "no perceivable symptoms" which is clearly wrong given the above. I've raised a formal complaint with The Motor Ombudsman (case accepted).

My suspicion is IBS sensor cable, connector, or wiring loom — the fault has never been fixed despite battery replacement, multiple code clears, and DCC basic settings.
It could be BMS, interested how to diag.


Has anyone had BCM or wiring loom replaced and resolved similar issues? Would be very interested to know.