OBD-II trouble code
B009E: Right Side Restraints Sensor 5 (Subfault)
A right flank restraints sensor has stopped reporting acceptably. If it is not the only sensor code stored, stop treating them as separate problems — on a modern restraints system the set of codes that arrived together is a map of the wiring, and it will point at the break.
Quick facts
- System
- Body
- Category
- Airbag / SRS Restraints
- Severity
- High severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $120 – $800
- DIY difficulty
- Shop recommended
What does B009E mean?
B009E is a hexadecimal body code — the character after B009 is the letter E — set by the airbag control module for one of the satellite sensors along the right side of the vehicle. The single most useful thing to understand about it is not what it says on its own, but how it behaves in company.
Satellite restraint sensors on modern vehicles are generally not analogue devices wired individually back to the module with a supply, a ground and a signal each. They sit on a dedicated two-wire peripheral sensor interface, a small point-to-point serial arrangement in which the same pair of wires carries the sensor's power and its data. The sensor draws current from the pair and signals by modulating that current; the module supplies the pair and decodes what comes back. The reason manufacturers moved to it is obvious once you count: a vehicle with eight or ten satellite sensors would otherwise need thirty conductors running into the restraints module, and the connector alone would be unmanageable. Two wires per sensor, and in some architectures a shared pair serving several sensors in sequence, keeps it sane.
That architecture rewrites the diagnosis. On a shared or daisy-chained pair, a single break does not take out one sensor — it takes out that sensor and everything downstream of it, all at once, all in the same key cycle. So a group of sensor codes is not evidence of a group of failed sensors. It is evidence of one fault, and the boundary between the codes that set and the codes that did not tells you physically where along the run the break is. The last sensor still reporting normally is upstream of the fault; the first one missing is at or beyond it. That is a location, derived from a code list, before anyone removes a trim panel. Conversely, a single sensor code with every other sensor on the same run reporting normally argues strongly for the sensor itself or for its own final connector, because a fault further back would have taken its neighbours with it.
The corollary is a warning about parts. Replacing several sensors because several codes are stored is how a straightforward wiring repair turns into an expensive one. Read the pattern first.
The vehicle drives normally throughout. Right side impact protection may not perform as designed, and the module has likely disabled part of the function rather than act on data it cannot verify. Restraint circuits contain pyrotechnic devices and the system must be safely powered down before any connector is disturbed.
Common causes
- Open or high resistance in the shared two-wire sensor bus, which takes out this sensor and every one downstream of it together
- Corroded or backed-out terminal at an inline connector partway along the run
- Failed sensor, which is the likely answer when this is the only code stored and its neighbours are reporting normally
- Short between the two bus wires, collapsing communication for the whole run
- Water intrusion at a low-mounted connector on the right side
- Harness damage from previous body, trim or seat work on that side
- Restraints module port or driver fault, which would typically take out an entire run at once
- Sensor mounting loose, so the device reports movement inconsistent with the rest of the structure
Symptoms
- Airbag or SRS warning light on and staying on
- B009E stored with a symptom byte, very often accompanied by other sensor codes from the same side
- Several sensor codes appearing simultaneously in the same key cycle rather than accumulating over weeks
- Codes returning as a complete group after being cleared
- No effect on engine, transmission or brake behaviour
- Fault appearing after seat removal, trim work or accident repair on that side
Diagnostic steps
- 1.Write down every restraints code stored, not just this one, and note which sensors are absent from the list. The boundary between reporting and non-reporting sensors is the most valuable piece of evidence available and it costs nothing to collect.
- 2.Obtain the wiring diagram for that side and establish the order the sensors sit in on the bus. Without the order, the code pattern cannot be turned into a location.
- 3.If several codes set together, treat it as one fault. The break is at or just before the first non-reporting sensor in the sequence, and the last one still reporting is upstream of it.
- 4.If this is the only code and its neighbours are fine, the fault is local: this sensor or its own connector, not the run.
- 5.With the system safely disabled per the manufacturer's procedure, inspect the inline connectors along the run before inspecting the sensors. Inline joints are where these buses fail.
- 6.Check the two-wire pair for continuity and for a short between the conductors, following the manufacturer's procedure for testing restraint circuits.
- 7.Check the sensor mounting and its fastener while the trim is off, since access is the expensive part of the job and it is worth verifying while you are there.
- 8.Resist replacing multiple sensors because multiple codes are stored. Prove the bus is good before any part is ordered.
Repair cost
$120 – $800
A connector or harness repair on the sensor bus is $150 to $450, and on a multiple-code presentation that is very often the entire fix. A single sensor replacement with the required system checks is $250 to $600 depending on how much trim and seat hardware has to come out. The failure mode this page warns about is the expensive one: replacing three or four sensors because three or four codes were stored can reach four figures and still leave the fault, because the fault was one break in a shared pair. Diagnosis time spent reading the pattern pays for itself here.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with wiring harness / circuit repair 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.