Passenger Occupant Classification System Malfunction
What does B0028 mean?
The B0028 code means the vehicle's onboard diagnostic system has detected: Passenger Occupant Classification System Malfunction. This is a critical severity code.
Common Symptoms
- Airbag warning light on
- Passenger airbag off light stays on or flickers
- SRS malfunction message
- Passenger airbag may not deploy appropriately
- Warning chime intermittent
Probable Causes (Ranked by Likelihood)
- Failed occupant classification sensor in passenger seat Very High
- Damaged wiring to occupant classification module High
- Defective occupant classification module under seat Moderate
- Seat cover or aftermarket cushion interfering with sensor Moderate
- SRS control module not receiving classification data Low
Step-by-Step Diagnostic Procedure
-
Scan SRS system for all DTCs
-
Check occupant classification sensor readings with scan tool
-
Inspect wiring under passenger seat for damage
-
Remove any aftermarket seat covers and retest
-
Verify occupant classification module operation
Frequently Asked Questions
What is the occupant classification system?
This system uses sensors in the passenger seat to determine the size and weight of the occupant, allowing the SRS system to adjust airbag deployment or suppress it entirely for small children.
Can an aftermarket seat cover cause this?
Yes. Thick seat covers or cushions can interfere with the pressure sensors in the seat, causing incorrect occupant classification readings.
Why is this code expensive to fix?
The occupant classification sensor is often integrated into the seat cushion and may require replacing the entire seat foam assembly, which is costly in both parts and labor.