What does the B0042 fault code mean?
The B0042 fault code, applicable to all car manufacturers, means “Third Row Left Frontal Stage 2 Deployment Control (Subfault)“.
Background Information: Newer cars use multi-stage airbags to regulate the pressure inside the airbag. The higher the pressure, the greater the intensity of the airbag deployment. The system automatically determines the airbag deployment intensity based on parameters such as collision intensity, passenger weight, seat belt usage, child seat presence, and distance from the airbag. This design ensures that the airbag deploys with moderate intensity in most collisions, reserving maximum intensity for the most severe collisions.
Symptoms of Error Code B0042
- The SRS/airbag indicator light illuminates on the dashboard;
- A warning message appears on the display (“Airbag malfunction” or similar);
- The SRS diagnostic system fails when starting the vehicle;
- The error may occur intermittently.
Main Causes of B0042 Fault Code
- Open circuit in the secondary airbag activation circuit;
- Damaged or corroded airbag connector;
- Airbag deployment defect (Stage 2);
- Faulty SRS module;
- Error after tampering with the safety system (e.g., after removing the steering wheel);
- Module reflashing or replacement without calibration.
B0042 Fault Code in Different Vehicles
B0042 in Chevrolet: This is common in Cruze, Malibu, and Aveo models. It is usually caused by a loose connection in the steering column connector.
B0042 in Opel: In Astra and Zafira models, this fault may occur after intervention or accessory installation on the steering column.
B0042 in Cadillac: This error is common in CTS and Escalade models and requires in-depth diagnosis and software adaptation.
B0042 in Buick: In Enclave and LaCrosse, the problem is usually related to corrosion of the steering column connector.
B0042 in GMC: It is most common in Terrain and Yukon models, often associated with wiring harness defects.
How to Diagnose Error Code B0042?
- Connect an OBD2 scanner and read the error codes.
- Disconnect the system: Disconnect the battery for at least 10 minutes to discharge the SRS circuit. Check the airbag connector under the steering wheel (Step 2) for damage or corrosion.
- Test the wiring between the airbag and the SRS module for open or short circuits.
- If no external damage is detected, check the resistance of the second-stage igniter.
Tools required: OBD2 scanner with SRS reading capability;Multimeter; electrical tape, heat shrink tubing, soldering kit (for wiring repair); special adapter or squib simulator (if necessary).
Possible Causes and Diagnostic Methods
| Possible Cause | How to Check？ |
|---|---|
| Open or short circuit in wiring | Check circuit integrity with a multimeter |
| Damaged or dirty connector | Visual inspection, cleaning, and reconnection |
| Igniter malfunction | Diagnosis via scanner, resistance testing |
| Control module problem | Read error and compare with system parameters |
How to fix error code B0042?
Simple Troubleshooting Methods
- Reset the error after disconnecting and reconnecting the airbag (if the connector is loose);
- Clean the contacts and replace corroded connectors;
- Reset the error after emergency deployment (if the airbag has been replaced).
In-depth Diagnosis and Repair Solutions
- Replace the squib or the entire airbag;
- Repair or completely replace the second-stage wiring;
- Replace the SRS module, followed by replacing its software configuration;
- Perform the “airbag calibration” procedure using dealer equipment.
Troubleshooting by Symptom
| Symptom | Possible Solution |
|---|---|
| SRS indicator does not turn off | Check the wiring and resistance of the igniter |
| Airbag only partially deploys | Check the second stage of the circuit, replacement may be necessary |
| Error does not reset after repair | Reset is required using a dealer scanner |
B0042 Error FAQ
Is it possible to drive with a B0042 fault code?
No, because the error is related to the airbag system. In an accident, the airbag may not deploy, increasing the risk of injury.
What are the most common causes of error B0042?
The most common causes are damage to the wiring, connectors, or the second-stage driver’s airbag itself.
Can I reset the B0042 error myself?
Yes, sometimes disconnecting the battery for 10-15 minutes helps. However, if the cause is not eliminated, the error is likely to reappear.
If a B0042 error occurs, should I replace the airbag?
Not necessarily. In some cases, repairing the contacts or wiring is sufficient. Airbag replacement is only necessary if the inflator is damaged.
How dangerous is the B0042 error?
This error is critical because it disables one of the driver’s airbag deployment stages. This significantly reduces the level of protection in an accident.
Related OBD2 errors for B0042:
B0020 – Left Side Airbag Deployment Control (Subfault)
B0040 – Third Row Left Side Airbag Deployment Control (Subfault)
B0051 – Driver Seatbelt Sensor (Subfault)
Important! If DTC B0042 is active, one or both airbag deployment stages may be disabled, potentially leading to complete airbag failure in an accident. Do not attempt to tamper with the SRS system before disconnecting the battery. If in doubt, consult a professional, as working with airbags requires extreme caution and expertise.