Broken or chafed wire in the side airbag harness, often at the seat flex point; Disconnected or poorly seated side airbag connector under the seat; Corroded terminals at the side airbag squib or seat harness connector; Failed side airbag inflator module with an open internal squib; Damaged clock spring or wiring in the seat belt pretensioner circuit sharing the loop; Water intrusion or rodent damage to the floor and seat harness

DTC codes / B00xx · Airbags, seats, doors, lights and comfort systems / B0042

B0042Side Deployment Loop Open (Generic)

Q: What does code B0042 mean?

Side Deployment Loop Open (Generic). B0042 indicates that the side airbag deployment loop is open, meaning the inflator circuit has a break in its wiring path. The airbag control module monitors the loop's resistance and sets this code when the circuit reads open instead of the expected closed path.

B0042 indicates that the side airbag deployment loop is open, meaning the inflator circuit has a break in its wiring path. The airbag control module monitors the loop's resistance and sets this code when the circuit reads open instead of the expected closed path.

SystemBody

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyProfessional

AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

Airbag warning light illuminated on the instrument cluster
Often no symptoms besides the warning light
Side airbag may be disabled and will not deploy in a collision
Intermittent warning light that flickers over bumps or when adjusting the seat
Seat-mounted side airbag connector may feel loose or show corrosion

Common causes, most likely first

Broken or chafed wire in the side airbag harness, often at the seat flex point
Disconnected or poorly seated side airbag connector under the seat
Corroded terminals at the side airbag squib or seat harness connector
Failed side airbag inflator module with an open internal squib
Damaged clock spring or wiring in the seat belt pretensioner circuit sharing the loop
Water intrusion or rodent damage to the floor and seat harness

How to diagnose and fix it

Scan all modules and record freeze-frame data to confirm B0042 is current, not history
Inspect the side airbag connector under the seat for looseness, corrosion, or pushed pins
Perform a wiggle test on the seat harness while watching live resistance data for the side loop
Measure resistance across the side airbag squib with the battery disconnected and module allowed to discharge
Check continuity of the side airbag harness from the module connector to the seat connector
Repair or replace the damaged harness section or connector terminals
Clear codes and verify the loop resistance reads within specification with no code returning

Before you replace the side airbag

A seat that slides back and forth constantly flexes the side airbag harness, and the break often hides inside the loom where visual inspection misses it.
The side airbag loop often shares a connector with the seat belt pretensioner, so a pretensioner fault can set B0042 even when the airbag itself is fine.
Aftermarket seat covers or audio installers frequently disturb the under-seat connector, creating an open circuit that looks like a failed airbag.
Resistance readings taken with a standard multimeter can be misleading because the meter's test current may not match the module's monitoring current.
A history B0042 that will not clear after a battery disconnect often points to a connector that was never fully latched, not a failed inflator.

Can I keep driving with B0042?

The vehicle is safe to drive mechanically, but the side airbag is disabled and will not deploy in a crash. Avoid collisions and have the circuit repaired promptly, especially if the warning light is steady rather than intermittent.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.