B0099Roll Over Sensor
- Generic OBD-II code · Body
- How the car detects it
- B0099 reports a fault in the rollover sensing that decides whether curtain airbags and pretensioners fire when a vehicle tips. Bosch integrates rollover sensors in its base airbag control unit, so the sensor is often part of the module. A Delphi patent shows the principle: roll rate and low-g vertical acceleration give roll angle and rate, which are compared with deploy and no-deploy curves, while a high-g lateral accelerometer acts as a separate arming check. FMVSS 226 requires a monitored readiness indicator where ejection mitigation deploys in a rollover; Karma recalled the 2018 Revero because its rollover sensing was not enabled. FCA uses the code: recall Y79 (2021 Grand Cherokee, 2022 Wagoneer) has technicians check for B0099-96 before reflashing the restraint controller, without defining it. The airbag lamp lights.
- What you may notice
- Airbag warning lamp on
- Curtain airbags and pretensioners may not fire in a rollover
- Safety note: airbag control unit with rollover sensing; work only de-energised (battery off, wait time) at a specialist workshop
- Likely causes
- LikelyInternal fault of the rollover sensor built into the airbag control unit (module replacement)
- PossibleAirbag unit loose, mounted at an angle or after a crash no longer within its fitting tolerance
- RareWiring or plug fault where a separate rollover sensor is fitted
- RareRestraint controller software or configuration not matching the vehicle
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €100 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.