Summary
B0028 indicates the airbag control module (ACM) has detected a fault in the right front (passenger side) seatbelt pretensioner deployment circuit. The pretensioner is a pyrotechnic device that rapidly retracts the seatbelt to remove slack in the first milliseconds of a collision. The most common cause is a wiring connector issue at the pretensioner (35%), followed by a failed pretensioner squib (30%) and ACM internal fault (15%). While the seatbelt itself still functions as a passive restraint, the pretensioner will not fire in a crash.
Severity: High — seatbelt pretensioner will not function in a collision
Safe to drive: Yes, cautiously — the seatbelt still works as a manual restraint, but won't tighten automatically in a crash
Repair cost: $150–$800 depending on cause
DIY difficulty: Moderate
What does B0028 mean?
Seatbelt pretensioners are part of the supplemental restraint system (SRS). In a crash, the ACM fires the pretensioner at the same time (or slightly before) the airbags deploy. The pretensioner uses a small pyrotechnic charge to retract the seatbelt webbing by 2–4 inches in about 10 milliseconds, pulling the occupant firmly into the seat before the airbag inflates. This removes any slack in the belt and positions the occupant correctly for optimal airbag interaction.
B0028 is set when the ACM detects an open circuit, short circuit, or out-of-range resistance in the right front pretensioner squib circuit. Like airbag squibs, the pretensioner squib has a specific resistance range (typically 1.5–4 ohms) that the ACM monitors continuously. Any deviation from this range means the ACM cannot guarantee the pretensioner will fire, so it disables that circuit and sets the code.
The pretensioner connector is located under the front passenger seat or at the base of the B-pillar, areas exposed to kicked debris, spilled liquids, and seat track movement. This makes the connector and wiring particularly vulnerable to damage.