B0042 on 2008-2014 Cadillac CTS: Airbag Light Causes and Fixes

What's Unique About the 2008-2014 Cadillac CTS

The 2nd generation Cadillac CTS, built on the GM Sigma II platform, is specifically called out in a widespread General Motors Technical Service Bulletin (TSB #08-09-41-002H) for intermittent airbag lights caused by faulty connector position assurance (CPA) retainers. This means that unlike many other vehicles where an airbag code might immediately point to a major component, on the CTS, the first suspect is often a tiny, inexpensive plastic clip on a wiring connector. This known issue, which affects dozens of other GM vehicles from the same era, makes diagnosing B0042 on this platform unique, starting with a simple connector inspection rather than assuming a major part has failed.

Diagnostic Flowchart

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

Generation note: The 2008-2014 model years cover the entire second generation of the Cadillac CTS. The primary TSB related to this issue, #08-09-41-002H, applies to all years within this generation, so the causes and fixes are consistent.

Symptoms You May Notice

• Airbag warning light is illuminated on the instrument panel.
• "Service Airbag" message may appear on the Driver Information Center (DIC).

Most Likely Causes

1. Loose or Damaged Connector Position Assurance (CPA) Retainer 🔴 High Probability This is a well-documented issue covered by GM Technical Service Bulletin #08-09-41-002H, which specifically includes the 2008-2014 CTS. The small plastic CPA clips on the yellow airbag connectors can become loose, break, or go missing, causing a poor connection and triggering the fault. This is a very common issue across many GM models of the era.
   How to confirm: After safely disabling the airbag system, locate the yellow airbag connectors (e.g., at the base of the steering column or behind the airbag module) and physically inspect the small plastic CPA clips to see if they are loose, broken, or not fully seated. A missing clip is a definitive sign.
   Typical fix: Replace the faulty CPA retainer (GM Part No. 88988974) and ensure the connector is fully seated. The CPA must be pushed in completely after the connector body is seated. In a pinch, some mechanics have used zip ties or silicone adhesive to secure the connection, but replacing the clip is the correct repair.
   Est. part cost: $5-$15
2. Failed Clock Spring (Steering Wheel Coil) 🟡 Medium Probability The clock spring contains a flexible ribbon cable that allows the steering wheel to turn while maintaining electrical contact with the driver's airbag. This cable can wear out and short over time from repeated turning, causing a 'resistance low' fault.
   How to confirm: If connector inspection doesn't reveal a problem, the clock spring is the next most likely cause. Diagnosis involves testing the circuit's resistance through the clock spring with a multimeter, which is a job for a professional. Swapping with a known good part is another diagnostic method.
   Typical fix: Replace the clock spring assembly inside the steering column. Requires steering wheel removal. 🎬 Watch: Step-by-step clock spring replacement on a Cadillac CTS-V.
   Est. part cost: $50-$290
3. Damaged Wiring or Terminals ⚪ Low Probability Wiring in the steering column or under the driver's seat can become chafed or pinched over time. Terminals in the connectors can also corrode or lose tension. The terminals are gold-plated for conductivity and are very sensitive.
   How to confirm: Visually inspect the wiring harness for any signs of damage. Check for corrosion or backed-out pins inside the connectors. This requires careful inspection after disabling the SIR system.
   Typical fix: Repair the damaged section of the wire or replace the affected connector terminal using the specified SIR terminal repair kit (GM P/N J-38125) to maintain circuit integrity. Do not use standard terminals.
   Est. part cost: $10-$50

Rare But Worth Checking

• Faulty Driver's Airbag Module: While possible, an internal short in the airbag module itself is much less common than wiring or clock spring issues. This should only be considered after all circuit integrity checks have been performed.
• Faulty Sensing and Diagnostic Module (SDM): Failure of the main airbag computer is very rare. The SDM should be the last component suspected and should be diagnosed by a professional technician. Sometimes an SDM setup procedure may need to be re-run after programming, but this is a separate issue.

Diagnosis Steps

1. CRITICAL SAFETY WARNING: The Supplemental Inflatable Restraint (SIR) system must be properly disabled before beginning any diagnosis or repair. This typically involves disconnecting the negative battery terminal and waiting at least 10-15 minutes for the system's backup power to discharge. Failure to do so can result in accidental airbag deployment and serious injury.
2. Connect a professional scan tool capable of reading GM-specific 'B' codes to confirm B0042 is the active or stored code.
🎬 Watch: How to reset the airbag light on GM vehicles.
3. Following the guidance in TSB #08-09-41-002H, locate the yellow SIR harness connectors related to the driver's airbag circuit, particularly at the base of the steering column and behind the airbag module itself.
4. Inspect the Connector Position Assurance (CPA) clip on the connector. Ensure it is not broken, loose, or missing. If it is, replace it with GM Part No. 88988974.
5. If the CPA is intact, disconnect the connector and inspect the terminals for corrosion, damage, or poor tension. The terminals are gold-plated; do not use standard connectors or probes.
6. If terminal repair is needed, use only the specified GM SIR terminal repair kit (J-38125) to avoid future resistance issues.
7. If all connectors and wiring appear visually sound, the next most probable cause is the clock spring. 🎬 See how to correctly center and set a new clock spring. This part requires removal of the steering wheel to access and replace.
8. If the issue persists after replacing the clock spring, a more advanced diagnosis of the wiring harness between the SDM and the clock spring for a short to ground or short between circuits is required.
9. As a final step, if the entire circuit tests good, the fault may lie within the driver's airbag module or the SDM, but these are the least likely causes.

Parts You'll Likely Need

• Connector Position Assurance (CPA) Retainer (OEM #88988974) — As identified in TSB 08-09-41-002H, this small plastic clip is a known failure point that leads to poor connections and airbag faults. It is the most likely and cheapest fix.
  Trusted brands: ACDelco (Genuine GM)
  OEM price range: $5-$15
  Aftermarket price range: $5-$10
• Clock Spring (OEM #23248441 (example, verify by VIN)) — This is a common wear-and-tear item. The internal ribbon cable fails, causing a short circuit that triggers the B0042 code.
  Trusted brands: ACDelco, Dorman (525-033), SKP, Standard Motor Products
  OEM price range: $170-$260
  Aftermarket price range: $50-$150

Related Codes That Often Appear With This One

• B0044 — B0044 is 'Driver Frontal Deployment Loop (Stage 2) Open'. Both B0042 and B0044 relate to the same circuit. An intermittent connection issue can cause the SDM to log either a 'Resistance Low' or an 'Open' fault at different times as the connection flickers.
• B0022 — B0022 is 'Driver Frontal Deployment Loop (Stage 1) Resistance Low'. Since the driver's airbag is a dual-stage system, a problem in the shared wiring or clock spring could potentially affect both stage 1 and stage 2 circuits, causing both codes to appear.

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) ... B0042 ... Set (Inspect and Replace Connector Position Assurance (CPA) Retainer). This is a widespread bulletin covering dozens of GM models from 2005-2014, indicating a common design or supplier issue with the CPA clips.

Platform-Specific Known Issues

• The 2008-2014 Cadillac CTS is explicitly listed in GM TSB #08-09-41-002H regarding intermittent airbag lights caused by faulty connector position assurance (CPA) retainers in the SIR system.

Mechanic-Grade Diagnostic Values

• Driver Frontal Deployment Loop (Stage 2) Resistance — expected: 1.3 - 4.8 ohms (Typical range for GM deployment loops). Failure: A resistance of less than 1.3 ohms for 500 milliseconds will set code B0042.

Hidden / Shadow Codes Worth Checking

• Symptom Bytes (e.g., 04, 0D, 0E): While not explicitly listed for B0042 in the search results, TSB 08-09-41-002H shows that GM uses symptom bytes for related SIR codes. These provide more specific fault details, such as 'short to ground' or 'short between circuits', which are critical for accurate diagnosis. (see via GM Tech2 or GDS2 professional scan tool.)

Scan Tool Commands That Help

• GDS2/Tech2 or equivalent professional scanner: Clear DTCs — This command must be issued after the physical repair is completed. The airbag light will not turn off on its own, even if the fault is fixed.
• Specialized EEPROM programming tools (e.g., CarProg): Clear Crash Data / Reset Internal Fault — This is an advanced procedure used if the SDM has locked itself due to a collision event ('crash data') or has an internal, non-clearing fault code. This is not typically required for a simple B0042 fault but is relevant for overall SDM service.

Wiring & Ground Locations

• Sensing and Diagnostic Module (SDM) — Located underneath the vehicle carpet under the center console.. This is the airbag control module that sets code B0042. Advanced diagnosis requires checking the wiring harness continuity from the steering column connector back to the SDM.
• Driver Airbag Connector — Behind the driver's airbag module in the center of the steering wheel.. This is one of the primary connection points covered by TSB 08-09-41-002H. The CPA retainer on this connector is a common failure point.
• Steering Column to Body Harness Connector — Typically located at the base of the steering column, connecting the clock spring wiring to the main body harness.. This is the other main connection point for the driver's airbag circuit and is also susceptible to the CPA retainer issue mentioned in the TSB.

OEM Part Supersession History

• 15899023, 20952441, 20982802, 25811625, 25941116 → 23248441 — Part consolidation and design updates by the manufacturer.
  Heads up: Part 23248441 is specified for models WITHOUT a heated steering wheel. A different part number is required for vehicles with this option.

Model Year Variations Within This Range

• 2008-2014: The clock spring part number is different for models equipped with the optional heated steering wheel. The common replacement part (23248441) is for non-heated wheels only. Using the wrong clock spring will result in either the airbag fault persisting or the heated wheel function being lost.