B0078 code meaning
Third Row Right Seat Belt Pretensioner Deployment Control
What B0078 means
B0078 refers to the right seat of the third row and its belt pretensioner. No carmaker publishes B0078 in this J2012 sense, and Mercedes models with third-row tensioning retractors log the right-hand unit as B00E6 instead. Like B0077, the number has a sensor meaning in GM's older Saab modules: the 2006 Saab 9-5 sets B0078 for an open or short in the communication with the passenger-side side-impact sensor, and the 9-3 airbag module (2003, 2007) uses it for the passenger-side B-pillar sensor, with bytes for faulty communication, a short to battery or ground, or a wrong sensor fitted. Where the code really concerns the right pretensioner of the third row, the airbag lamp is on and that seat loses its pretensioning until the loop is repaired.
B0078 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of B0078
- Airbag warning lamp on
- Third-row right occupant without pretensioning, or on Saab impaired side-impact detection on the passenger side
- Safety note: pyrotechnic restraint parts; only work on them with the battery disconnected, after the wait time, at a specialist workshop
Common causes of B0078
- Most likelyOn older Saab 9-3/9-5, fault at the passenger-side side-impact or B-pillar sensor (older GM meaning)
- PossiblePlug at the third-row right belt loosened when the seat was folded or removed
- Less likelyInternal fault of the third-row right pretensioner
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Third row right pretensionerSquib circuitSRS control module
What each part of B0078 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). |
| 78 | The exact fault in that area. |
What to do next
- Note B0078 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 B0078
What does B0078 mean?
B0078 means "Third Row Right Seat Belt Pretensioner Deployment Control". B0078 refers to the right seat of the third row and its belt pretensioner. It is a generic code, so it means the same on every make.
Is it safe to drive with B0078?
B0078 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will B0078 fail an emissions test?
B0078 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 B0078 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will B0078 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.