B0090 B0xxx · Body (B) High severity
Restraint System Crash Sensor Fault
One of the impact sensors feeding the airbag ECU is out of range or not communicating. Deployment logic becomes unreliable.
Severity guidance: High — stop driving and diagnose now; risk of further damage
Symptoms you will notice
- Airbag lamp on
- Possible false deployment risk or no deployment
Common causes
Ordered from most to least likely — start at the top.
- 1 Failed impact sensor
- 2 Corroded or damaged connector
- 3 Front-end damage not fully repaired
- 4 Wiring harness damage
How to diagnose it
Cheapest and least invasive first — most of these codes are not a parts problem.
- ✓ Inspect for previous accident damage first — a bent bracket or unrepaired harness is common.
- ✓ Read which sensor the ECU flags (front, side, satellite).
- ✓ Check the connector and mounting orientation; sensors are direction-sensitive.
- ✓ Compare sensor readings with key-on data.
Repair options
- Replace the impact sensor
- Repair the harness
- Repair any residual accident damage
B0090 — frequently asked questions
Can the sensor be re-used after a crash? +
Manufacturer guidance is generally to replace impact sensors after a deployment. Follow the manual.
Does mounting direction matter? +
Yes — an incorrectly oriented sensor may not trigger in the intended impact type.
Confirm the diagnosis before you buy parts
Send us the code, freeze-frame data and the vehicle — our engineers will tell you what to test first.