B0042 on 2005-2010 Pontiac G6: Airbag Light Causes and Fixes

What's Unique About the 2005-2010 Pontiac G6

The Pontiac G6 is built on the GM Epsilon platform, which it shares with vehicles like the Chevrolet Malibu, Saturn Aura, and Saab 9-3. This entire family of vehicles from this era is known for intermittent airbag light issues due to faulty connector designs. GM released a comprehensive Technical Service Bulletin (TSB #08-09-41-002H) that directly addresses this problem across dozens of models, including the G6. The TSB points to a small, brittle plastic clip called a Connector Position Assurance (CPA) retainer as the primary culprit. This makes the G6 and its platform mates highly susceptible to this specific, inexpensive failure, where the fix is often related to securing a connection rather than replacing a major, costly component like the airbag module itself.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Airbag warning light illuminated on the instrument panel
• "Service Airbag" message on the driver information center (DIC)
🎬 Watch: How to identify and fix SRS warning lights

Most Likely Causes

1. Loose, Broken, or Missing Connector Position Assurance (CPA) Retainer 🔴 High Probability This is a well-documented, widespread issue across many GM platforms of this era, including the Pontiac G6, as outlined in TSB #08-09-41-002H. The small plastic CPA clips on the yellow airbag connectors become brittle and fail, causing a poor connection. The TSB notes that the main connector can feel seated even when the CPA is not, which is what causes the fault.
   How to confirm: After disabling the SIR system, visually inspect the yellow airbag connectors. Key locations are under the driver's seat and at the base of the steering column. Visually inspect the yellow airbag connectors at the back of the driver's airbag module and at the clock spring. Check if the small plastic CPA retainer (often orange, yellow, or green) is cracked, missing, or not fully seated. Wiggling the connector may cause the light to flicker if it's an intermittent fault.
   Typical fix: Reseat the main connector body, then push the CPA retainer in until it clicks. If the CPA is broken or missing, it must be replaced with a new one (GM Part #88988974). Applying a small amount of dielectric grease to the terminals is also a recommended practice.
   Est. part cost: $5-$15
2. Loose or Damaged Airbag Harness Connector 🟡 Medium Probability Wiring under the seats can be disturbed by moving the seat, by items stored underneath, or by corrosion. A user on a Ram forum noted that simply having their vehicle cleaned triggered the light, which was resolved by reseating the under-seat connectors.
   How to confirm: Wiggle the yellow connectors under the driver's seat while monitoring the code status with a scan tool (if possible). A change in status indicates a poor connection. Visually inspect the connector terminals for corrosion, pushed-out pins, or other damage.
   Typical fix: Disconnect and reconnect the harness to ensure it is fully seated. If terminals are corroded or damaged, they may need to be cleaned or the connector pigtail may need to be replaced. In some related recalls for other GM vehicles, the final fix was to remove the connector entirely and solder the wires.
   Est. part cost: $15-$40 for a new pigtail connector
🎬 See this walkthrough on how to replace an airbag connector
3. Faulty Clock Spring (Steering Wheel Coil) ⚪ Low Probability The clock spring is a wear item that contains the wiring for steering wheel controls and the airbag. Constant turning of the steering wheel can eventually cause the internal ribbon cable to break or short circuit. A YouTube video demonstrates this failure on a 2006 G6, leading to a clock spring replacement.
   How to confirm: This is typically diagnosed after confirming the connectors and CPA retainers are good. Other symptoms may include failure of steering wheel-mounted controls (radio, cruise control) or a noise when turning the wheel. A scan tool can monitor resistance values while turning the steering wheel lock-to-lock; fluctuations or spikes indicate a bad clock spring.
   Typical fix: Replacement of the clock spring assembly within the steering column. This requires removing the steering wheel airbag and the steering wheel itself. 🎬 Watch: Pro tips for a successful clock spring replacement
   Est. part cost: $50-$180

Rare But Worth Checking

• Faulty Sensing and Diagnostic Module (SDM): This is the airbag control module, located under the center console. It is rarely the cause of the problem and should only be considered after all wiring, connector, and clock spring issues have been definitively ruled out.

Diagnosis Steps

1. WARNING: The SIR (airbag) system must be disabled before beginning any diagnosis or repair. Disconnect the negative battery terminal and wait at least 10-30 minutes for the system capacitors to fully discharge.
2. Scan the SDM for the specific B-series fault code using an SRS-compatible scan tool. Confirm B0042 is present, and note if it is current or history. Check for any symptom bytes.
3. Referencing TSB #08-09-41-002H, locate the yellow SIR harness connectors. The most likely locations are under the driver's seat and at the base of the steering column.
4. Visually inspect the connector and its Connector Position Assurance (CPA) retainer. The CPA is a small plastic clip (often orange or yellow) that locks the main connector in place.
5. If the CPA is loose, broken, or missing, replace it with GM Part #88988974. Ensure the main connector is fully seated, then lock the new CPA in place. You should hear or feel a click.
6. If the CPA is intact, disconnect the connector and inspect the terminals for corrosion, damage, or poor pin tension. Clean with electrical contact cleaner and apply dielectric grease before reconnecting.
7. If no visible issues are found with the connectors, the next step is to test the clock spring circuit. Using a scan tool, monitor the 'Driver Airbag Resistance' parameter while turning the steering wheel lock-to-lock. The value should remain stable within the specified range (approx. 1.3-4.8 Ohms). Wild fluctuations or dropouts indicate a failed clock spring.
8. As a final check, inspect the main chassis grounds related to the SIR system, such as G201 (under the center console) and G105 (on the transmission stud), for looseness or corrosion.
9. After any repair, reconnect the battery and use an SRS-compatible scan tool to clear the fault code and verify the airbag light goes out. The light will not turn off on its own.

Parts You'll Likely Need

• Connector Position Assurance (CPA) Retainer (OEM #88988974) — This small plastic clip is the most common failure point identified in GM's own service bulletin (TSB #08-09-41-002H) for causing code B0042. It becomes brittle and fails to secure the connector.
  Trusted brands: ACDelco, GM Genuine Parts
  OEM price range: $5-$15
  Aftermarket price range: $5-$10
• Clock Spring (OEM #20940370) — If connector issues are ruled out, the clock spring is the next most likely cause due to wear and tear from steering wheel rotation. It contains the electrical ribbon for the airbag.
  Trusted brands: ACDelco, Dorman, Standard Motor Products
  OEM price range: $100-$180
  Aftermarket price range: $50-$150

Related Codes That Often Appear With This One

• B0044 — This code is for 'Driver Frontal Deployment Loop Open'. B0042 (low resistance/short) and B0044 (open circuit) can be triggered by the same intermittent connector issue, depending on how the connection fails at any given moment.
• B0022 — This code is for 'Driver Frontal Deployment Loop Stage 1 Resistance Low'. It is common to see B0022 and B0042 together as they refer to the two different deployment stages of the same driver's airbag. A single faulty connector can affect both circuits.

Technical Service Bulletins (TSBs) & Recalls

• 08-09-41-002H: Diagnostic Information for Supplemental Inflatable Restraint (SIR) System, Intermittent AIR BAG Indicator/Lamp Illuminated with DTC(s) B0012... B0042 or B0044 Set (Inspect and Replace Connector Position Assurance (CPA) Retainer). This is the primary document for this issue.

Platform-Specific Known Issues

• This vehicle is explicitly listed in GM Technical Service Bulletin #08-09-41-002H, which details how an intermittent airbag light with code B0042 can be caused by a faulty Connector Position Assurance (CPA) retainer on an airbag system connector.
• Owners on Reddit and other forums frequently report "Service Airbag" messages on the G6, with many confirming that fixing a loose connector under the seat or in the steering column resolved the issue.
• A user on 2CarPros.com described an intermittent airbag light that appeared when turning the steering wheel, a classic symptom pointing towards a failing clock spring or a wire being stressed in the steering column.

Mechanic-Grade Diagnostic Values

• Driver Frontal Deployment Loop Stage 2 Resistance — expected: 1.3 - 4.8 ohms. Failure: A reading less than 1.3 ohms for 500 milliseconds will set DTC B0042.
• Sensing and Diagnostic Module (SDM) Ground Circuit Resistance — expected: < 0.1 ohms. Failure: Resistance higher than 0.1 ohms indicates a poor ground connection at a location like G201 or G105, which can cause various intermittent SIR faults.
• Airbag Simulator Resistor (for testing) — expected: 2.0 - 2.5 ohms. Failure: When diagnosing, a special tool with this resistance is used to substitute the airbag. This helps determine if the fault is in the airbag module itself or in the wiring/clock spring. Most GM vehicles use a ~2.2 Ohm standard.

Hidden / Shadow Codes Worth Checking

• B0042 02 / B0042 0D / B0042 0E: These are symptom bytes that provide more detail. '02' or '0D' can mean 'Resistance Low' or 'Resistance Above Threshold', while '0E' specifically indicates 'Resistance Below Threshold'. All point to a short or low resistance condition. (see via A professional GM-specific scan tool like a Tech2 or GDS2 is required to view these two-digit symptom bytes.)

Scan Tool Commands That Help

• GM Tech2 / GDS2: Live Data > Deployment Loop Resistance — This is essential for diagnosing a faulty clock spring. A technician monitors the resistance value in real-time while turning the steering wheel from lock to lock. Unstable readings, spikes, or dropouts that coincide with wheel movement point to a failure in the clock spring's internal ribbon cable.
• GM Tech2 / GDS2: Clear DTCs — After a repair is completed, the fault code must be manually cleared from the Sensing and Diagnostic Module (SDM). The airbag light will not turn off on its own even if the fault is fixed. Standard OBD-II readers cannot clear SIR/airbag codes.

Wiring & Ground Locations

• Sensing and Diagnostic Module (SDM) — Under the center console.. This is the airbag system's computer. All deployment loop wiring originates here. While the module itself rarely fails for this code, its connectors and ground are important check points.
• G201 — Under the center console, on a front support bracket.. This is a primary ground for several interior modules, including the SDM on some GM platforms. A poor connection here can cause intermittent and difficult-to-diagnose SIR faults.
• G105 — On the left rear side of the engine compartment, on an engine/transmission stud.. This ground is shared by the Engine Control Module and Transmission Control Module. While not a direct SIR ground, a severe issue here can cause widespread electrical noise and unpredictable behavior in other modules. A YouTube video on a G6 with a bad G105 ground showed numerous seemingly unrelated electrical issues.
• BCM (Body Control Module) Connectors — On the passenger side of the center console.. The BCM communicates with the SDM. While not directly part of the deployment loop, its connectors can be disturbed during console work, and a wiring diagram shows the driver door trigger (Gray/Black wire) terminates here, which can be relevant for related diagnostics.

OEM Part Supersession History

• 15278147, 15925947, 21994380 → 20940370 — Standard part evolution and consolidation by the manufacturer.
  Heads up: Part 20940370 is the correct service replacement clock spring for the 2005-2010 Pontiac G6. Using an incorrect or non-OEM clock spring may resolve the airbag light but cause other issues like non-functional steering wheel controls.
• → 88988974 — This is the designated service part for the CPA retainer referenced in TSB 08-09-41-002H.
  Heads up: This is a small, orange plastic clip. Ensure you are purchasing the genuine GM or ACDelco part to guarantee correct fit and material properties.