What does code B0081 mean?
Code B0081 stands for Passenger Presence System.
Smaller passengers, such as children, can be injured by an airbag deployment. The passenger presence system (PPS) is designed to monitor the type of occupant sitting in the front passenger seat. This is information is used to disable the front passenger airbag unless there is a person of substantial weight in the passenger seat.
The PPS is a sub-portion of the supplemental restraint system (SRS), which is the airbag system. The PPS consists of the following components:
- PPS Control module
- Sensor in the seat
- A wiring harness
- A passenger on/off indicator
Airbag / Image source
A sensor in the front passenger seat informs the PPS computer (referred to as a module) as to whether or not an adult-sized occupant is sitting in the seat. To do this, the sensor transmits and receives a low-level electric field into the seat. The PPS communicates passenger information to the main SRS control module, the sensing and diagnostic module (SDM). In turn, the SDM turns on, disables or turns off the front passenger airbag as needed.
A dash-mounted status indicator is also part of the PPS. If the airbag is enabled, the indicator displays "Passenger Airbag On". If the airbag is disabled, the indicator displays "Passenger Airbag Off". The SDM sends a message to the instrument cluster to turn the indicator on or off.
The SDM communicates regularly with the PPS module. If there is a problem with the PPS, the SDM sends the instrument cluster a request to turn on the SRS malfunction indicator. Code B0081 indicates the SDM has detected a problem with the PPS module. The SDM will default to disabling the passenger airbag when this code is set.
B0081 symptoms
Common causes for B0081
Code B0081 is typically caused by one of the following:
- Wiring issues
- Control module problems
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How to diagnose and repair B0081
Perform a preliminary inspection
Sometimes B0081 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.
When code B0081 is set, it's also important to check the part #s on the SDM and PPS to ensure they're correct. It's possible that one of the modules was previously replaced with an incorrect unit.
Note: General Motors has a TSB for this problem which involves a loose PPS connector.
Check for other DTCs
The SDM will set code B0081 if the PPS module has a diagnostic trouble code (DTC) stored. Accessing these DTCS may indicate problems elsewhere that are affecting PPS module operation. Any additional DTCs should be addressed prior to diagnosing B0081.
Check the circuit
Code B0081 often sets when the SDM cannot communicate with the PPS module. Before condemning the PPS module, the circuit between the SDM and PPS should be checked. This can be done using a digital multimeter (DMM). In addition, the PPS module's circuit should be checked for proper power and ground.
Check the modules
In some cases, the PPS module may be the problem. However, before condemning the module, ensure its software is up to date. It may be possible to program the module instead of replacing it.
In rare cases, the SDM may also be to blame. If replacing the PPS module doesn't work, the SDM probably needs to be replaced.
Other diagnostic codes related to B0081
Code B0081 does not have any directly related codes.
Code B0081 technical details
There are often two-digit sub-codes associated with B0081. These codes indicate what type of circuit defect the control module has detected. Here is an example from a General Motors vehicle.
- Sub-code 00 indicates the sensing and diagnostic module (SDM) has detected a faulty present in the passenger presence module.
- Sub-code 3A indicates the sensing and diagnostic module (SDM) has determined the incorrect passenger presence system module is installed.
- Sub-code 4B indicates the passenger presence system module is not calibrated.
- Sub-code 5A indicates the passenger presence system module has lost communication with the SDM.
