B00A0 OBD-II: Occupant Classification System (Subfault)

What does code B00A0 mean?

Code B00A0 stands for Occupant Classification System (OCS).

Children and small passengers can be injured during airbag deployment. The occupant classification system (OCS) is designed to prevent this from happening. To keep small individuals, such as children safe, the OCS prevents the passenger airbag from deploying when needed. The OCS is part of the airbag system, referred to as the supplemental restraint system (SRS).

The OCS identifies passenger size, out of position passengers and the presence of a child seat in the front passenger seat. Typically, an under seat-mounted occupant sensor(s) is used to collect data for the OCS. Information from these sensors is sent to the OCS control module (basically the OCS computer). The OCS control module then sends the information to the main SRS module, referred to as the airbag control module. The airbag module then decides whether the passenger airbag should be deployed in the event of a crash.

Code B00A0 indicates the airbag module has detected a problem with the OCS system.

Airbag / Image source

B00A0 symptoms

• Illuminated warning lights
• SRS system performance issues

Common causes for B00A0

Code B00A0 is typically caused by one of the following:

• Wiring issues
• A faulty OCS sensor
• Control module problems

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How to diagnose and repair B00A0

Perform a preliminary inspection

Sometimes B00A0 can pop up intermittently. This is especially true if the code is a history code and not current. Clear the code and see if it returns. If it does, the next step is to perform a visual inspection. A trained eye can check for issues such as broken wires and loose connections. If a problem is found, the issue should be repaired and the code cleared. If nothing is discovered, check for technical service bulletins (TSBs). TSBs are recommended diagnostic and repair procedures put out by the vehicle manufacturer. Finding a related TSB can greatly reduce diagnostic time.

Check the circuit

Code B00A0 often sets when the airbag module cannot communicate with the OCS module. Before inspecting the sensor or control module, the OCS circuit should be checked. A professional will usually do this using a digital multimeter (DMM). Since the OCS module is located under the seat, it's common for its wiring to get caught in the seat tracks or damaged by debris. The OCS module circuit should also be checked directly to ensure the module has good power and ground. Any problems should be repaired as needed and the code cleared.

Check the sensors

Although some vehicle manufacturers don't suggest it, it may be possible to test the OCS sensors. This can be done using a DMM. Some sensors can also be checked using a diagnostic scan tool connected to the vehicle's diagnostic port. The sensor circuit should also be checked for proper power and ground. Repairs should be made as needed and code cleared.

Check the modules

The repair information from many manufacturers jumps right to module replacement for code B00A0. Usually, the suggestion is to replace the OCS module first. Then, if that doesn't work, the next step is to replace the airbag module. However, it's a good idea to check the software in both modules before replacement. In some cases, if there's a TSB or an update, the module may be able to be reprogrammed instead of replaced.

Other diagnostic codes related to B00A0

• B00A1: Code B00A1 indicates the airbag control module has detected a problem with the occupant position system.

Code B00A0 technical details

There are often two-digit sub-codes associated with B00A0. These codes indicate what type of circuit defect the control module has detected. Here is an example from a Ford vehicle:

• Sub-code 09 indicates the airbag module has detected a OCS module component failure.
• Sub-code 4A indicates the airbag module has detected an incorrect OCS module is installed.
• Sub-code 63 indicates the airbag module has detected an incorrect OCS module circuit protection time out.
• Sub-code 64 indicates the airbag module has detected an incorrect OCS module signal plausibility failure.