What Does B0099 Mean?
DTC B0099 indicates the Body Control Module (BCM) or safety restraint control module has detected an internal fault or signal abnormality within the roll over sensor system. This sensor is critical for deployment timing of side curtain airbags and rollover protection systems during a vehicle overturn event. The subfault designation suggests either an intermittent signal, sensor calibration error, internal sensor circuit malfunction, or a communication issue between the sensor and control module.
Safety Warning
Vehicle should not be driven until repaired as the rollover protection and side curtain airbag deployment may be disabled or compromised. In the event of an actual rollover accident, occupant protection systems may fail to deploy properly, significantly increasing injury risk.
Common Causes
45%
Faulty roll over sensor internal accelerometer or gyroscope component failure
25%
Damaged or corroded wiring harness connector at roll over sensor
20%
BCM or airbag control module software calibration issue or internal fault
10%
Low vehicle battery voltage causing sensor initialization or communication errors
Diagnostic Steps
1
Step 1: Perform a visual inspection of the roll over sensor mounting location (typically center console area or under a front seat) for physical damage, water intrusion, or loose mounting. Check battery voltage with multimeter; must be 12.4V+ with engine off, 13.8-14.5V running.
2
Step 2: Inspect the roll over sensor connector for corrosion, bent pins, or moisture. Disconnect and reconnect to ensure proper seating. Measure resistance across sensor ground circuit to vehicle chassis ground; should be less than 1 ohm.
3
Step 3: Using scan tool live data, monitor roll over sensor voltage outputs and angle readings while vehicle is stationary on level ground. Compare readings to manufacturer specifications (typically 2.5V reference at rest with +/- 0.5V variance for lateral/longitudinal axes).
4
Step 4: Perform a sensor re-initialization or calibration procedure through scan tool if available. Clear codes and road test on level surface, monitoring for fault recurrence. If fault returns immediately without vehicle movement, sensor internal failure is confirmed.
5
Step 5: If sensor data appears normal, check for BCM/airbag module software updates or technical service bulletins. Verify control module ground connections are clean and tight with less than 0.5 ohm resistance to battery negative.
6
Step 6: Replace roll over sensor if all electrical circuits test within specifications but fault persists. After replacement, perform mandatory sensor calibration procedure and verify airbag system readiness indicator extinguishes.
Estimated Repair Cost
$200 - $800
Parts + labor, varies by vehicle and location
DTC B0099 indicates the Body Control Module (BCM) or safety restraint control module has detected an internal fault or signal abnormality within the roll over sensor system. This sensor is critical for deployment timing of side curtain airbags and rollover protection systems during a vehicle overtur...
The most common cause of B0099 (Roll Over Sensor (Subfault)) is: Faulty roll over sensor internal accelerometer or gyroscope component failure
Typical repair costs for B0099 range from $200 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle should not be driven until repaired as the rollover protection and side curtain airbag deployment may be disabled or compromised. In the event of an actual rollover accident, occupant protection systems may fail to deploy properly, significantly increasing injury risk.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B0099 to identify the root cause.
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Quick Info
Category
Body
System
Supplemental Restraint System (SRS) / Airbag System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
