B0079 code meaning
Driver Seat Belt Pretensioner B Deployment Control
What B0079 means
B0079 marks the driver's second (B) pretensioner. Mercedes-Benz uses the code in exactly this way: in LI54.21-P-070658, valid for A-Class, CLA and GLB, B007913 is an open circuit in the squib of the belt end fitting tensioner on the driver's side, while the retractor of the same seat appears as B007E. An end fitting or anchor pretensioner pulls on the lower belt anchor next to the door side of the seat and so tightens the lap section; GM's restraint guide and a Hyundai-Kia patent describe this layout. Older Saab models give the number another meaning: the 2006 Saab 9-5 stores B0079 when an incorrect driver-side side-impact sensor is installed. A stored B0079 lights the airbag lamp and means the driver's lap tensioner may not fire.
B0079 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of B0079
- Airbag warning lamp on
- Driver's lap belt section not tightened in a crash
- Safety note: the end fitting tensioner is pyrotechnic; never probe it live – battery off, wait time, specialist workshop
Common causes of B0079
- Most likelyPlug at the driver's belt end fitting tensioner beside the seat loose or corroded
- PossibleLead to the end fitting tensioner pinched by the seat rail
- Less likelyOn a 2006 Saab 9-5, wrong side-impact sensor fitted (older GM meaning)
- Less likelyInternal fault of the end fitting tensioner squib
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Driver pretensioner bSquib circuitSRS control module
What each part of B0079 means
| B | Body system: airbags, seat belts, power seats, lights and climate control. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 79 | The exact fault in that area. |
What to do next
- Note B0079 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about B0079
What does B0079 mean?
B0079 means "Driver Seat Belt Pretensioner B Deployment Control". B0079 marks the driver's second (B) pretensioner. It is a generic code, so it means the same on every make.
Is it safe to drive with B0079?
B0079 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will B0079 fail an emissions test?
B0079 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is B0079 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will B0079 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.