B1780 on Lexus: How to Diagnose & Fix
Theft Lock / Anti-Theft System Enabled (manufacturer-specific)
1 Lexus model · 1 documented issue · 1 critical
B1780 on Lexus by model: symptoms, diagnosis and fix
Multiple 2022-2024 Lexus LX owners reported persistent SRS/airbag warning messages and dealer diagnoses related to the front passenger occupant classification system and related airbag components. This generation shares Toyota/Lexus safety-system campaigns affecting front seat occupant sensing and airbag readiness, and owners describe warning lights, repeated dealer visits, and concerns about whether the passenger airbag will deploy correctly. Because the issue directly affects restraint-system operation, it is considered high severity even when the repair itself is covered by recall or warranty.
Common Symptoms
- SRS warning light illuminated
- Airbag system malfunction message
- Passenger airbag OFF/ON status behaving abnormally
- Warning appears after moving front passenger seat
- Repeated dealer visits for airbag-related faults
How to Fix
Scan the SRS system with a Toyota/Lexus-capable diagnostic tool and inspect the passenger seat weight/occupant classification components, seat harnesses, and any applicable recall campaign status by VIN. Dealers typically perform recall remedies, recalibration, or replacement of affected seat sensor/airbag-related parts, then clear codes and verify the occupant detection status with a seat calibration procedure. If the warning returns, wiring under the seat and connector tension should be checked carefully.
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B1780 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does B1780 mean on a Lexus?
B1780 stands for "Theft Lock / Anti-Theft System Enabled (manufacturer-specific)." B1780 is a manufacturer-specific body code; on General Motors vehicles it is commonly listed as the anti-theft (Theft Lock) system being enabled, meaning the immobilizer/security function has activated and may be inhibiting normal operation. It indicates a security/anti-theft state or fault rather than a mechanical failure. Depending on the make and circumstances it can be informational or can be associated with a crank/no-start condition. Confirm the exact definition for the specific vehicle. On Lexus it is documented across 1 model: LX.
What are the most common causes of B1780?
The most common causes of B1780 are: Anti-theft system triggered or not yet relearned, Unrecognized or unprogrammed key/transponder, Faulty ignition lock cylinder or anti-theft sensor, Wiring or connector fault in the security circuit, Discharged or weak battery during start, Faulty body control or anti-theft module. The specific cause varies by vehicle.
How much does it cost to fix B1780 on a Lexus?
Repair costs vary widely with the root cause and Lexus model; each issue on this page carries its own estimate where one is published.
Looking for B1780 on a different make?
View B1780 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.