OBD-II trouble code
B009D: Right Side Restraints Sensor 4 (Subfault)
A restraints sensor on the right flank is not reporting acceptably. On a left-hand-drive vehicle the right side is the kerb side, and that single geographic fact predicts most of what goes wrong here far better than any general theory about sensor failure.
Quick facts
- System
- Body
- Category
- Airbag / SRS Restraints
- Severity
- High severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $100 – $700
- DIY difficulty
- Shop recommended
What does B009D mean?
B009D is a hexadecimal body code — the character after B009 is the letter D — stored by the airbag control module and naming a satellite crash sensor on the right side of the vehicle. In the abstract it is the mirror of the equivalent left side code. In practice the two sides do not live the same life at all, and the difference is worth taking seriously before you start testing.
On a left-hand-drive vehicle, the right side faces the kerb. Every parking manoeuvre puts that flank alongside a concrete edge, a bollard or a wall. Wheels rub kerbs on the right far more often than on the left, and the impacts that result are transmitted through the rocker and the sill — precisely the structure that side sensors are bolted to. The right side also collects the water. Roadside puddles, gutter run-off and the spray thrown up by the nearside wheels all land on that flank, and low-mounted sensors and connectors in the rocker area take the worst of it. Add road salt in winter and the corrosion timeline on the right side runs visibly ahead of the left on the same vehicle. So when a right side sensor code appears, physical inspection for impact and corrosion deserves to come before electrical testing, which is the reverse of the usual instinct.
There is a second thing that is specific to this side rather than the other, and it changes how you read companion codes. On many vehicles the passenger side restraints are gated by occupant detection. The module knows whether the front passenger seat is occupied, and roughly how heavy the occupant is, and it uses that to decide whether to deploy and at what stage. That machinery only exists on the right side of a left-hand-drive car. The result is that a right side restraints fault frequently arrives alongside occupant classification codes, and the relationship can run either way — a shared supply or ground problem in that side of the vehicle can take out both, or an occupant sensing fault can leave the module unable to make a deployment decision it would otherwise make from this sensor's data. Reading them together, rather than chasing each in isolation, usually gets there faster.
Drivability is unaffected. The vehicle starts, runs and stops exactly as before. What has changed is that right side impact protection may not perform as designed, and the module has likely disabled part of the function rather than act on a sensor it does not trust. The system contains pyrotechnic devices and must be safely powered down before anything is unplugged.
Common causes
- Kerb strike or parking impact transmitted through the rocker or sill, disturbing the sensor or its mounting
- Corrosion at a low-mounted connector on the kerb side, accelerated by gutter water and road salt
- Water intrusion into the sensor connector
- Shared supply or ground fault on the right side of the vehicle, often showing up alongside occupant classification codes
- Failed satellite sensor
- Harness chafed or crushed after previous body or trim work on that side
- Sensor mounting fastener loose or the mounting face corroded, so structural movement is not read correctly
- Open, short or high resistance in the sensor circuit back to the module
Symptoms
- Airbag or SRS warning light on and staying on
- B009D stored with a symptom byte in the restraints module
- Passenger airbag status indicator behaving oddly, if occupant sensing on that side is also affected
- Occupant classification codes stored at the same time
- Fault appearing after a kerb strike, a parking scrape or work on that side of the vehicle
- Intermittent fault that correlates with wet weather
- No effect on engine, transmission or brake behaviour
Diagnostic steps
- 1.Walk the right side of the vehicle before connecting anything. Look along the sill and rocker for scrapes, distortion and evidence of a kerb strike. On the kerb side this is a genuinely productive first step rather than a formality.
- 2.Record every restraints code stored, including occupant classification codes. The passenger side carries occupant detection that the driver side does not, and the two systems share circuits.
- 3.With the system safely disabled per the manufacturer's procedure, inspect the sensor connector for corrosion, green deposits and water. Kerb-side connectors corrode measurably earlier than their left side counterparts on the same vehicle.
- 4.Check the sensor's mounting fastener and the condition of the mounting face. A sensor that is not rigidly attached to structure cannot read intrusion correctly, and a corroded face is enough to compromise that.
- 5.If several right side codes are stored together, test the shared supply and ground for that side before testing any individual sensor. One bad ground is a far more likely explanation than several failed sensors.
- 6.Inspect the harness along the rocker and under the sill trim for crush damage, particularly if the vehicle has been jacked or lifted at a non-standard point.
- 7.Verify supply and ground at the sensor against specification.
- 8.Repair corrosion properly, sealing the connector afterwards. A cleaned but unsealed kerb-side connector will be back within a season.
Repair cost
$100 – $700
A corroded connector cleaned, repaired and properly resealed runs $120 to $350, and on the kerb side that is the single most likely outcome. A satellite sensor replacement with the required system checks is $250 to $600 depending on trim access. If a kerb strike has distorted the mounting or the sill, the cost extends into bodywork and is no longer really about this code. SRS diagnostic time alone is typically $100 to $200. All of it is professional work because of the pyrotechnic devices in the system.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with airbag / srs crash sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
Leave this one to a qualified shop. It typically involves emissions-critical components, refrigerant handling, or other work that requires manufacturer-grade tooling, training, or certification. DIY attempts often produce a more expensive problem than the original code.