Damaged or disconnected left curtain airbag electrical connector, especially at the airbag module or under the headliner; Broken wire in the left curtain deployment loop, often from chafing at a body seam or hinge point; Corroded or loose terminal in the left curtain airbag circuit; Failed left curtain airbag inflator or module with an open internal squib; Faulty restraint control module driver circuit for the left curtain loop; Water intrusion or collision damage affecting the left curtain wiring harness

DTC codes / B00xx · Airbags, seats, doors, lights and comfort systems / B0046

B0046Left Curtain Deployment Loop Open

Q: What does code B0046 mean?

Left Curtain Deployment Loop Open. B0046 means the restraint control module has detected an open circuit in the left side curtain airbag deployment loop, so the circuit cannot fire the inflator as designed. The module monitors loop resistance and continuity, and it sets this code when the measured resistance is far above the expected range or the circuit is completely broken.

B0046 means the restraint control module has detected an open circuit in the left side curtain airbag deployment loop, so the circuit cannot fire the inflator as designed. The module monitors loop resistance and continuity, and it sets this code when the measured resistance is far above the expected range or the circuit is completely broken.

SystemBody

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyProfessional

AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

Airbag or supplemental restraint system warning light illuminated on the instrument cluster
Often no symptoms besides the warning light, with the vehicle driving normally
Airbag system disabled or a message indicating service restraint system on some vehicles
Intermittent warning light that appears when driving over bumps or turning
Left curtain airbag will not deploy in a side impact or rollover event

Common causes, most likely first

Damaged or disconnected left curtain airbag electrical connector, especially at the airbag module or under the headliner
Broken wire in the left curtain deployment loop, often from chafing at a body seam or hinge point
Corroded or loose terminal in the left curtain airbag circuit
Failed left curtain airbag inflator or module with an open internal squib
Faulty restraint control module driver circuit for the left curtain loop
Water intrusion or collision damage affecting the left curtain wiring harness

How to diagnose and fix it

Scan all restraint control module codes and record freeze-frame data before clearing anything
Inspect the left curtain airbag connectors and wiring for damage, corrosion, or loose pins
Measure resistance across the left curtain deployment loop at the module connector and compare to specification
Disconnect the left curtain airbag and check the loop resistance to isolate whether the open is in the wiring or the inflator
Repair or replace the damaged section of the left curtain wiring harness and clear the code
If wiring and connectors are good, substitute a known-good left curtain airbag or module only after confirming the open is internal
Verify repair by clearing codes and confirming the restraint system self-test passes without resetting B0046

What the open loop really tells you

An open circuit code does not always mean the airbag itself failed; a disconnected connector under the headliner or a chafed wire at a body seam is a very common cause that technicians miss when they replace the airbag first.
The restraint control module measures loop resistance with a small test current, so a poor terminal tension or corrosion can set B0046 intermittently without any visible wire break.
After any collision repair or headliner work on the left side, the left curtain connector is frequently left unplugged or partially seated, which sets this code immediately.
B0046 can be stored alongside side impact sensor or seat belt pretensioner codes when a shared ground or harness path is damaged, so always check for related codes before condemning the curtain airbag.
Never use a standard ohmmeter on an airbag squib without first disconnecting the module and following service precautions, because the meter's test current can be dangerous and give false readings.

Can I keep driving with B0046?

The vehicle is safe to drive normally because the left curtain airbag simply will not deploy, but the restraint system is compromised in a side impact or rollover. Avoid any driving that could lead to a side collision or rollover until the fault is repaired, and have the system diagnosed promptly.

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.