OBD-II trouble code
B0049: Third Row Right Frontal Stage 1 Deployment Control (Subfault)
One of three codes covering the same right-hand third-row position, which makes counting them the fastest diagnosis available — and on a vehicle with a rebuilt or salvage history, the count usually points somewhere other than a new fault.
Quick facts
- System
- Body
- Category
- Airbag / SRS Restraints
- Severity
- High severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $110 – $1,100
- DIY difficulty
- Shop recommended
What does B0049 mean?
Three separate deployment codes are defined for the right-hand third-row position: the side airbag and the two stages of the frontal airbag. That grouping gives this particular code a diagnostic shortcut the others do not have, and it is worth using before any tools come out.
The arithmetic is straightforward. A pyrotechnic squib is a simple, extremely reliable device with no moving parts and no wear mechanism in normal service. The probability of one failing on a given vehicle in a given year is very small, and the probability of two or three failing at once is that small number multiplied by itself. So a single code from this group is consistent with an individual fault; two or three together are not. When B0049 arrives with B004A, the stage 2 loop of the same airbag, the shared item is that inflator's connector — one plug carrying both loops, which explains both codes with one fault. When B0049 arrives with B0048 as well, the shared item moves further upstream to the harness junction serving the whole right-hand third-row area, or to the module connector. Counting the codes tells you how far up the tree to start.
There is a second explanation for a cluster like this that has nothing to do with wiring, and it needs stating because it comes up often in the used market. Once a squib has fired, its loop reads open forever. A vehicle that has been in a deployment crash and been repaired will set a code for every loop that was not properly replaced — and cutting corners on rear airbags is a known shortcut on cheap rebuilds, because those positions are expensive, easy to overlook and invisible from the driver's seat. A block of restraints codes on a vehicle with a rebuilt, salvage or reconstructed title should be read as a question about the quality of the repair rather than as an electrical puzzle. If you are looking at buying such a vehicle, a full restraints scan before purchase costs very little and can reveal that the airbags simply were not put back.
Where the code stands alone on a vehicle with clean history, it means the module found the stage 1 loop outside the resistance window a squib circuit must occupy. Stage 1 is the charge that fires in every deployment of the bag, so this loop being out of range is the version that can cost the deployment entirely rather than merely reducing its energy.
Equipment scope applies here as it does across this family: a dedicated third-row frontal airbag is rare, and build data should confirm the device exists before its circuit is diagnosed. The fault does not affect how the vehicle drives, and the loop contains a live explosive device that must be powered down before it is disturbed.
Common causes
- Airbag not replaced after a previous deployment, leaving the loop permanently open — common on rebuilt and salvage-title vehicles
- Shared inflator connector fault, which sets this code together with the stage 2 code for the same bag
- Upstream harness or module connector fault, which sets this code together with the side airbag code for the same position
- Open circuit at a rear SRS connector disturbed during trim, cargo or accessory work
- Damaged insulation shorting the loop to ground or to a neighbouring circuit
- Failed stage 1 squib in an otherwise intact multi-stage inflator
- Salvage or non-matching airbag assembly fitted with a loop resistance outside the module's expected band
- Restraints control module fault, to be considered only after the wiring and history are accounted for
Symptoms
- SRS or airbag warning lamp on and unable to be cleared
- B0049 accompanied by B004A, or by both B004A and B0048, in the same scan
- Multiple restraints codes on a vehicle with a rebuilt, salvage or reconstructed title
- Symptom byte indicating an open circuit, which is what a spent squib reports
- Code returning immediately on the next key cycle after being cleared
- No effect on engine performance, transmission behaviour, braking or steering
- Evidence of prior collision repair in the rear of the vehicle on close inspection
- Other restraints loops reporting normally, since each is monitored independently
Diagnostic steps
- 1.Count the restraints codes first. One code from this position suggests an individual fault; two or three together point at a shared connector or an upstream harness junction, because simultaneous squib failures are statistically implausible. This step costs nothing and frequently redirects the entire diagnosis.
- 2.Check the vehicle's title and repair history. A block of open-circuit restraints codes on a rebuilt or salvage vehicle very often means airbags were never replaced after a deployment, and no amount of circuit testing will find a fault that is really a missing component.
- 3.Inspect for evidence of prior rear-end or side collision repair — mismatched paint texture, replaced trim, aftermarket harness splices in the rear quarter. Prior repair quality is the most productive line of enquiry when the codes arrive as a group.
- 4.Record every symptom byte before clearing anything. Open circuits point one way and shorts another, and a spent squib reports specifically as an open, which is diagnostic in itself.
- 5.Power down the restraints system by the manufacturer's procedure and observe the specified capacitor discharge interval before any connector is separated.
- 6.Measure the stage 1 and stage 2 loops separately with the approved restraints tester. One loop out of range with the other normal points at the inflator; both out of range points at the connector they share. Never place a general-purpose multimeter across a deployment loop.
Repair cost
$110 – $1,100
Where the cause is a shared connector, one repair clears the whole group of codes and the cost stays near diagnostic level — $110 to $220 for the scan plus modest labor. Wiring and connector repair in the rear quarter runs $180 to $500. A multi-stage frontal airbag assembly is $350 to $900 fitted, and the part number must match, since a substitute with different loop resistance will simply reset the code. On a rebuilt vehicle missing several airbags the total can run well into four figures across all positions, which is exactly why a restraints scan is worth doing before such a vehicle is purchased.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with airbag control module (sdm) replacement / reset 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.