B0125 is a body code whose position in the standardized SAE list is reserved, meaning the standard assigns it no definition. Some code lists label it a night vision control module code, others leave it blank, and generic scan tools display whichever label their database carries. That label is not the vehicle's definition. Body codes in the B00xx and B01xx range are mostly standardized for restraint systems (airbags, pretensioners, occupant sensing) and a few body functions, and any number the standard leaves open is defined, if at all, by the manufacturer.
Severity: unknown until the definition is known. Can you keep driving? Usually. Body codes rarely affect the engine or brakes. If the code comes with a warning light for airbags, seat belts or a driver-assist system, treat that light as the guide: an airbag light means a restraint fault to fix before a long trip; a convenience-system light means an inconvenience.
Why a generic definition can be wrong
The OBD standard fixes definitions for powertrain codes that emissions inspectors need to read. Body and chassis codes are only partly standardized. A manufacturer is free to use a reserved number for anything in its own systems, and the same number can mean different things across brands. A generic tool that shows "night vision control module" for B0125 on a vehicle with no night vision system is displaying a label from a list, not reading the vehicle.
Two things follow: the code must be re-read with a tool that carries the manufacturer's own definitions, and the module that stored it must be identified, because body codes are stored by the module that found the fault, not by a central computer.
How to find the real definition
- Identify the module that stored B0125. A capable tool lists codes by module: restraints, body control, instrument cluster, driver-assist camera, and so on. The module narrows the meaning at once.
- Read the code with manufacturer-specific definitions, from the factory tool or a professional tool with the right vehicle database, and read any symptom byte after the code.
- Match the code to the warning light or the complaint. A restraint code arrives with the airbag light; a lighting or door code arrives with a body symptom.
- Search the manufacturer's service information for the code and module together. If the vehicle has a night vision or infrared camera system and the storing module is that system's controller, the generic label may be right; if not, it is not.
- Diagnose the circuit the manufacturer's definition names, in the order that applies to nearly all body codes: power and ground to the module, its connector, its wiring, the device, and the module last.
Causes, in general, for a body module code
Low battery voltage, which sets a spread of body codes across modules during cranking.
A connector or wire on the circuit the definition names.
A device the module monitors, such as a sensor, a lamp or a squib.
A module replaced or programmed without configuration, so it reports faults on equipment the vehicle does not have.
The module, last.
Frequently asked questions
Can I drive with a B0125 code?
Usually. Body codes rarely affect the engine or brakes. Let the warning light guide you: an airbag light means fix it before a long trip; a convenience-system light means it can wait for a scheduled visit.
What does B0125 mean?
In the standardized list, nothing; the number is reserved. Some tools label it a night vision control module code from one manufacturer's list. The vehicle's own definition, read from the module that stored the code with a tool that carries the manufacturer's database, is the only reliable meaning.
Why does my scan tool show a definition for a reserved code?
Because generic tools carry a database that fills reserved numbers with whatever one manufacturer used them for. The label is a guess. Re-read the code with manufacturer-specific definitions before acting on it.
How much does it cost to fix B0125?
Reading it correctly costs a diagnostic visit. The repair depends entirely on what the manufacturer's definition names, from a connector to a module.
Related codes
- B0001 to B0099: standardized restraint system deployment and sensor codes; see B0001.
- U-series codes stored alongside, which point at module communication rather than a device; see U codes and module communication.
- The general question of what a code does and does not tell you is covered in what a trouble code does not tell you.
The code number itself tells you the family and the domain; how to read an OBD2 code number explains what each character means and why body codes are only partly standardized.