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B0077 – 3rd Row Center Seat Belt Pretensioner Deployment Control (OBD2)

B0077 means "3rd Row Center Seat Belt Pretensioner Deployment Control". The airbag control module constantly measures the resistance of each airbag and pretensioner igniter circuit (deployment loop); a resistance outside the window means that airbag may not deploy.

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B0077 quick summary

Fault codeB0077
Meaning3rd Row Center Seat Belt Pretensioner Deployment Control
SystemBody
VehiclesGeneric OBD2
SeverityHigh
Can I drive?The car drives normally, but the affected airbag may not deploy in a crash. Have it repaired promptly.
Repair cost€20 – €600

How airbag deployment loops are monitored

Each airbag and seat belt pretensioner has an igniter connected to the airbag control module. The module checks the resistance of every loop many times per second. Too low means a short, too high means an open or poor contact.

There is one code for each airbag, stage and pretensioner position – driver and passenger frontal airbags (often in two or three stages), knee airbags, side and curtain airbags, rear-seat airbags, seat belt pretensioners and load limiters. The code tells you which position to check; the test method is the same for all of them.

The most common causes are connectors under the seat that are not fully latched or are corroded, damaged wiring after seat adjustments or removal, and a worn clock spring (driver airbag).

The code refers to a seat in the 3rd row. Not every vehicle has this position – if your car has no 3rd seat row, the code points to a configuration or wiring fault rather than a real component.

B0077 is a body code from the standard (SAE) restraint system range. Some manufacturers use their own numbering for airbag codes, so always check the text your scan tool shows for your vehicle.

Symptoms of B0077

  • Airbag warning light on
  • Code appears after seat removal or interior cleaning
  • Light comes and goes when moving the seat
  • No driving symptoms
  • Failed technical inspection

Most common causes of B0077 (most likely first)

Mechanic's Pro Tip

Moving the seat fully forward and back while watching live data often reveals a chafed seat harness – the resistance jumps at a certain position.

  1. 1.Seat connector not fully latched or corroded

    Most likely

  2. 2.Wiring damaged under the seat

  3. 3.Faulty airbag or pretensioner igniter

  4. 4.Shorting bar in the connector not opening

  5. 5.Airbag control module fault

Step-by-step diagnostic guide

  1. 1

    Read the airbag module

    Read the codes and the measured loop resistance if available.

  2. 2

    Disconnect safely

    Disconnect the battery and wait the time specified by the manufacturer.

  3. 3

    Inspect connectors

    Check the connectors under the seat or behind the trim; reseat and clean them.

  4. 4

    Use an airbag simulator

    Replace the airbag with a resistor simulator to test the wiring and module (never measure an igniter with a normal ohmmeter).

  5. 5

    Repair and clear

    Repair wiring or replace the faulty component, clear codes and confirm the light goes out.

Frequently asked questions

Can I keep driving with B0077?

The car drives normally, but the affected airbag may not deploy in a crash. Have it repaired promptly.

How much does it cost to fix B0077?

Typical repair costs are 20 € – 600 €, depending on the cause and the vehicle. The most common fixes are: seat connector not fully latched or corroded; wiring damaged under the seat; faulty airbag or pretensioner igniter. Always confirm the cause with the tests above before buying parts.

Is it safe to unplug airbag connectors?

Only with the battery disconnected and after waiting the specified time. Otherwise the airbag can deploy.

Why did the airbag light come on after cleaning the car?

Moving or removing seats can loosen the airbag and pretensioner connectors under them.

What is the difference between B0077 and similar codes?

B0077 belongs to a group of codes for the same component that differ in the type or location of the fault: B0074 – 2nd Row Center Seat Belt Pretensioner Deployment Control; B0075 – 2nd Row Right Seat Belt Pretensioner Deployment Control; B0076 – 3rd Row Left Seat Belt Pretensioner Deployment Control; B0078 – 3rd Row Right Seat Belt Pretensioner Deployment Control; B0079 – Driver Seat Belt Pretensioner B Deployment Control; B007A – Passenger Seat Belt Pretensioner B Deployment Control. The tests on this page apply to the whole group; the type of fault tells you where to start.

Related fault codes

This guide is for information only. Working on vehicles can be dangerous — if you are unsure, have the car checked by a qualified mechanic. Values can differ between model years; always check the manufacturer's repair information.