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B0043 — Third Row Left Frontal Stage 3 Deployment Control

Generic OBD-II · all makesBody

OBD-II code B0043 indicates a fault in the deployment control circuit for the third row left frontal Stage 3 airbag. This typically means the system has detected an electrical issue that could prevent proper airbag deployment in a crash.

Symptoms

What causes it — most likely first

1. Faulty third row left frontal Stage 3 airbag module

The airbag module itself may have an internal fault, such as a short or open circuit, preventing proper deployment control.

2. Damaged or corroded wiring or connectors

Wiring harnesses or connectors leading to the airbag module may be damaged, corroded, or shorted, disrupting the deployment control signal.

3. Faulty clockspring (if applicable to third row)

In some vehicles, a faulty clockspring (which maintains electrical connections to moving parts) may affect the deployment control circuit.

4. Blown fuse or faulty relay in the airbag system

A blown fuse or malfunctioning relay in the airbag control circuit can prevent proper power delivery to the Stage 3 deployment control.

5. Faulty Occupant Classification System (OCS) sensor (if integrated)

If the vehicle uses an OCS to determine seat occupancy, a faulty sensor may incorrectly influence airbag deployment control.

6. Faulty SRS (Supplemental Restraint System) control module (rare)

While uncommon, a failure in the SRS control module could incorrectly trigger or inhibit the deployment control signal for this airbag.

How it's diagnosed

  1. Retrieve and document all stored diagnostic trouble codes (DTCs) using an OBD-II scanner with SRS capability.
  2. Visually inspect the wiring harness and connectors for the third row left frontal Stage 3 airbag for damage, corrosion, or loose connections.
  3. Check the airbag module and surrounding area for signs of physical damage or moisture intrusion.
  4. Test the resistance and continuity of the deployment control circuit wiring using a multimeter, following manufacturer specifications.
  5. Inspect the relevant fuses and relays in the airbag system for proper operation.
  6. If no wiring or connector issues are found, test the airbag module itself using manufacturer-recommended procedures or replace it if faulty.

Code facts & related codes

SystemBody
StandardizationSAE generic — identical on every make
Related codesB0040 — Third Row Left Side Airbag Deployment B0041 — Third Row Left Frontal Stage 1 DeploymB0042 — Third Row Left Frontal Stage 2 DeploymB0048 — Third Row Right Side Airbag DeploymentB0049 — Third Row Right Frontal Stage 1 Deploy

Vehicles this code applies to

The definition is universal; the diagnostics are engine-specific. Open your vehicle for the codes documented for it:

2020 Lexus ES3502020 Lexus GS350

Frequently asked

Is the SRS control module usually the cause of B0043?

No, the SRS control module is rarely the cause of this code. Most B0043 issues stem from faulty airbag modules, wiring problems, or connector issues. Replacing the control module should only be considered after all other potential causes have been ruled out.

Can I drive my vehicle with a B0043 code?

While the vehicle may still operate normally, the airbag system may not function correctly in a crash. It is recommended to diagnose and repair the issue as soon as possible to ensure occupant safety.

Will disconnecting the battery clear this code?

Disconnecting the battery may temporarily reset the code, but it will likely return if the underlying issue is not addressed. The airbag warning light will also remain illuminated until the fault is properly diagnosed and repaired.

Do I need special tools to diagnose B0043?

Yes, diagnosing airbag system codes typically requires an OBD-II scanner with SRS capability and a multimeter. Manufacturer-specific service information may also be necessary for accurate testing procedures.