What it means
This code identifies a fault associated with the third row left frontal stage 2 deployment control. The restraint control module sets it when it detects a problem in that deployment control; the exact fault is specified by accompanying subfault information.
How it works
The restraint control module monitors the stage 2 deployment control for the third-row left frontal airbag. B0042 indicates a fault in that stage's deployment control; the accompanying subfault information narrows down the electrical problem.
Common causes
Most likely first.
- Third row airbag wiring or connector fault
- Open or shorted deployment circuit
- Faulty airbag module
- Restraint control module fault
Symptoms
- Airbag warning light on
- Third row left frontal airbag stage may be unavailable in a crash
How to diagnose it
- Read the restraint control module with an SRS-capable scan tool and record B0042's subfault and event data before clearing the code.
- With the vehicle safely powered down according to the manufacturer's procedure, inspect the third-row left frontal airbag's stage 2 wiring and connectors for damage, looseness, corrosion, or signs of repair.
- Follow the manufacturer's wiring diagram and SRS-safe test procedure to check the stage 2 circuit for an open or short.
- Check stage 2 circuit continuity, terminal contact, and resistance using the manufacturer's procedure and specification; avoid direct inflator measurements unless expressly specified.
- If the stage 2 circuit passes, use the prescribed diagnosis to determine whether the airbag module or restraint control module is responsible.
Common fixes
- Repair damaged wiring in the third-row left frontal stage 2 deployment circuit.
- Correct a loose or corroded stage 2 connector using the manufacturer's SRS repair method.
- Replace the airbag module if testing confirms a fault in its stage 2 deployment control.
- Repair or replace the restraint control module if the circuit and airbag module pass and module testing confirms the fault.
Can I keep driving?
The third-row left frontal airbag's stage 2 may be unavailable in a crash; arrange prompt SRS diagnosis and avoid using that seating position until the fault is repaired. Handle its wiring only under the manufacturer's airbag safety procedure.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.