What it means
The restraint control module detected a fault associated with the roll over sensor. It sets the code when the sensor signal or its circuit fails the module's monitoring checks.
How it works
The rollover sensor provides information about vehicle roll to the restraint control module, which uses it to assess rollover protection needs. B0099 sets when the module finds that the rollover sensor signal or its circuit fails monitoring; a module fault is also possible if the sensor circuit checks out.
Common causes
Most likely first.
- Faulty roll over sensor
- Damaged or loose wiring
- Corroded connector
- Restraint module fault
Symptoms
- Airbag warning light
- SRS warning message
- Rollover protection may not work as intended
How to diagnose it
- Use an SRS-capable scan tool to confirm B0099 and inspect stored event data or status to determine whether the fault is present now.
- Locate the rollover sensor using service information and check for impact damage, incorrect mounting, or signs of recent disturbance.
- Follow the manufacturer's SRS disable procedure before inspecting the sensor connector and harness for looseness, corrosion, or physical damage.
- Test the rollover sensor wiring for opens, shorts, and poor connections using the vehicle wiring diagram and specified method.
- If the wiring passes, test the rollover sensor and restraint control module according to the manufacturer's procedure.
Common fixes
- Reconnect and secure a loose rollover sensor connector.
- Repair damaged wiring or corroded connector terminals.
- Correct damaged or improper sensor mounting.
- Replace the rollover sensor if it fails the specified test.
- Repair or replace the restraint control module only after confirming it is the source of the fault.
Can I keep driving?
Rollover protection may not operate as intended, and other SRS functions could also be affected depending on the vehicle. Minimize driving and arrange prompt diagnosis; do not handle SRS components without following the manufacturer's safety procedure.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.