BYD B1792 means the front passenger seat belt pretensioner stage 2 circuit is not connected — the SRS control module cannot detect the second squib (initiator) of the dual-stage passenger seat belt pretensioner.
What B1792 means
BYD vehicles equipped with dual-stage seat belt pretensioners use two pyrotechnic squibs per pretensioner to allow the restraint system to adjust retraction force depending on collision severity. The SRS control unit monitors each squib circuit independently for continuity and resistance within an expected window (typically 2-3 ohms per squib for OEM systems). B1792 is set when the SRS ECU measures the second squib (stage 2) of the front passenger seat belt pretensioner as an open circuit — meaning no continuity is detected. This could indicate a broken squib internally, a disconnected connector in the pretensioner wiring, or a fault in the SRS harness between the pretensioner and the SRS module. The consequence is that in a collision requiring dual-stage pretensioner activation, only stage 1 will fire — the restraint effectiveness is compromised for the front passenger. B1792 will illuminate the SRS warning lamp and disable the full dual-stage pretensioner function until the fault is corrected.
Symptoms
- SRS/airbag warning light illuminated on the instrument cluster and staying on
- B1792 stored in the SRS ECU fault memory (requires SRS-capable scan tool to read)
- Front passenger seat belt pretensioner stage 2 will not deploy correctly in a collision
- No drivability or powertrain effect — the fault is isolated to the SRS system
- Stage 1 of the pretensioner may still be functional; only the dual-stage capability is compromised
Common causes
- Failed stage 2 squib inside the passenger seat belt pretensioner unit — internal open circuit in the pyrotechnic element due to age, mechanical damage, or manufacturing defect
- Disconnected or partially seated connector at the seat belt pretensioner assembly — the pretensioner connector may have been displaced during seat adjustment or previous service work
- Damaged SRS wiring in the passenger seat harness — the SRS squib wires run beneath the seat and are vulnerable to damage from seat slider operation
- Corroded pretensioner connector — B-pillar-mounted pretensioner connectors on some BYD models are exposed to moisture from door seals
- SRS ECU internal fault affecting the stage 2 monitoring channel (uncommon; replace only after excluding all wiring causes)
Diagnostic approach
- Read the full SRS fault code with a BYD-compatible scan tool and note the fault type — Connect a scan tool with BYD SRS access (BYD DS scan tool, Autel MaxiSys with BYD coverage, or Launch X431 with BYD module). Read B1792 fault detail — the SRS ECU typically distinguishes between 'not connected' (open circuit) and 'short' conditions. A 'not connected' or 'open circuit' type fault confirms a broken squib or disconnected connector.
- DO NOT probe the squib circuit directly with a standard multimeter — The SRS squib circuits can carry an ignition voltage capable of deploying the pretensioner. Never probe squib terminals with a standard multimeter or test light. Only use an approved SRS resistance tester (typically built into a professional SRS scan tool that applies a safe low-current stimulus) to measure squib circuit resistance safely.
- Inspect the passenger seat belt pretensioner connector and harness — Disconnect the vehicle battery and wait a minimum of 3 minutes for the SRS backup capacitor to discharge before touching any SRS connector. Then locate the passenger seat belt pretensioner connector (at the B-pillar or on the seat belt retractor mechanism). Inspect for corrosion, pushed-back pins, or a connector not fully latched. Re-seat and latch the connector, reconnect the battery, clear B1792, and verify whether it returns.
Make & model notes
BYD: BYD Atto 3 / Yuan Plus (2022-2025): B1792 on this model is most commonly associated with the passenger seat B-pillar pretensioner connector working loose — the connector is located in a high-flex area of the B-pillar trim. Inspect the connector latch carefully; a half-latched connector can cause an intermittent open that returns after vehicle vibration.
BYD: BYD Han EV/DM (2020-2025): seat rail items (floor mats caught in the slider, objects dropped under the seat) are a known wiring damage risk on this platform — SRS squib wiring runs under the front seat carpeting. Inspect under both front seats before assuming the pretensioner itself has failed.
FAQ
Is it safe to drive a BYD with B1792?
The vehicle will drive normally, but front passenger safety in a collision is reduced — the seat belt pretensioner may not fully activate, which affects how well the seat belt restrains the passenger in a high-severity impact. We strongly recommend repairing B1792 before carrying passengers in the front seat.
Will B1792 fail an annual vehicle inspection?
Yes, in most markets. An illuminated SRS warning light is typically an automatic fail item in vehicle safety inspections. B1792 must be repaired and the warning light cleared before the vehicle will pass inspection.
Can the SRS warning light for B1792 be cleared without repair?
The code can be cleared with a scan tool, but B1792 will return on the next ignition cycle as the SRS module performs its startup self-test and immediately re-detects the open squib circuit. Permanent resolution requires repairing the physical fault — reconnecting the connector or replacing the pretensioner unit.