Infiniti EX35, EX37, QX50 & QX55 Seat Belt Pretensioner and SRS Faults
This guide covers common seat belt assembly failures, SRS warning light diagnosis, and critical safety information for owners of the 2008-2025 Infiniti EX and QX series SUVs.
- This is a critical safety component; professional installation and SRS module resetting are mandatory.
- An illuminated SRS/airbag light means your vehicle's entire airbag and pretensioner system is likely disabled and will not function in a crash.
- When buying a used part, you must verify it came from a non-wrecked vehicle and that the pretensioner has not been deployed.
- Always match part numbers carefully, as Infiniti used different versions depending on the vehicle's production date and interior color.
Symptoms of a Failing Seat Belt Assembly
A problem with a seat belt assembly isn't just an inconvenience; it's a major safety issue. If you notice any of these symptoms in your 2008-2012 Infiniti EX35, 2013 Infiniti EX37, 2014-2025 INFINITI QX50, or 2022-2024 INFINITI QX55, the component needs immediate attention.
- SRS or Airbag Warning Light is On: This is the most common and serious symptom. The SRS control module continuously monitors all safety components. If it detects high or low resistance in the pretensioner's circuit, it will illuminate the warning light on your dashboard. This indicates a fault in the system, and as a result, the airbags and pretensioners may not deploy in a crash.
- Slow or No Retraction: The seat belt webbing retracts slowly, or you have to manually feed it back into the pillar. This can be caused by dirt and grime on the belt or a weakened spring inside the retractor mechanism. 🎬 Watch: How to fix a slow or non-retracting seat belt
- Belt is Locked or Jammed: The belt will not pull out at all. This often happens after a collision where the pretensioner has deployed. Even a minor impact can be enough to fire the pretensioner.
- Frayed or Damaged Webbing: Visible cuts, tears, or fraying on the belt material compromise its strength and ability to restrain you in a crash.
- Random Locking: The retractor locks up during normal, slow extension of the belt, without any sudden vehicle movement. This points to a malfunction in the retractor's internal locking mechanism.
Known Issues, Recalls, and Technical Service Bulletins (TSBs)
While widespread, systemic issues with the seat belt assemblies on these specific models are not commonly reported, several recalls have affected related Infiniti vehicles. It is always best to check with an authorized dealer or the NHTSA website with your VIN to confirm if any open recalls apply to your vehicle.
- NHTSA Recall 24V132000 (Infiniti QX60): While not for the QX50/QX55/EX models, a recent recall for the 2024 Infiniti QX60 involved a missing rivet in the lap belt pretensioner assembly. This highlights the importance of component integrity in the SRS system. An unsecured pretensioner may not restrain an occupant as intended, increasing injury risk.
- General SRS Recalls: Other Infiniti models have had recalls related to the SRS system, such as driver's airbag inflators that may absorb moisture and deploy improperly. Always verify your specific vehicle's status.
Warning: The seat belt assembly contains a pyrotechnic pretensioner. Mishandling this component can cause accidental deployment, leading to serious injury. Installation, diagnosis, and replacement must be performed by a qualified professional technician with experience in SRS systems.
🎬 See this walkthrough on replacing a seat belt pretensionerBuying a Used Seat Belt Assembly
Purchasing a used OEM seat belt assembly can be a cost-effective solution, but it requires careful inspection to ensure it is safe and functional. A used part from a vehicle that has been in a collision is unsafe and unusable.
- Confirm Non-Deployment: This is the single most important check. A deployed pretensioner is a one-time-use device. The belt will be locked and will not extend. Do not purchase any seat belt assembly that is locked or shows any signs of having been fired.
- Inspect the Webbing Thoroughly: Pull the belt out to its full length. Look for any cuts, fraying, burns, or stiff sections. Any damage to the webbing means the part is unsafe and should be rejected.
- Check the Connectors: Examine the electrical connector for the pretensioner. Ensure it is not cracked, corroded, or have any bent pins. A clean, secure connection is vital for communication with the SRS module.
- Verify Part Numbers: Infiniti may use different part numbers based on production date, color, and vehicle features. The initial prompt noted a change for early 2019 QX50 models versus later ones. Always match the part number from your original assembly or verify compatibility with the seller using your vehicle's VIN.
- Source from a Reputable Recycler: Buy from a supplier who guarantees the part is from a non-wrecked vehicle and offers a warranty. Ask about the donor vehicle's history if possible.
Professional Installation and SRS System Reset
Replacing an SRS component is not a DIY job. The legal and safety implications are significant.
- Liability: Improperly installing a safety device like a seat belt pretensioner can carry significant legal liability in the event of an accident where the device fails to perform correctly. Many jurisdictions have laws against installing non-functional or counterfeit SRS components.
- SRS Module Reset: After a pretensioner deploys, the SRS control module stores permanent crash data. This data must be cleared with specialized equipment; a standard OBD-II scanner cannot do this. Failure to reset the module will keep the airbag light on and the entire safety system will remain inoperative.
- System Calibration: After replacement, a technician must perform a full diagnostic scan to ensure the new component is communicating correctly with the SRS module and that the entire system is free of faults and ready to function.
Pro Tip: Before replacing the seat belt assembly, a technician should always perform a diagnostic scan. The SRS light can be triggered by other components, such as a faulty clock spring, occupant classification sensor, or the SRS module itself. Proper diagnosis prevents unnecessary replacement of expensive parts.
Cost Breakdown
Prices can vary based on location, supplier, and the specific part number for your vehicle's trim and color.
| Part Type | Estimated Cost |
|---|---|
| New OEM | $350 - $550 |
| New Aftermarket | Not commonly available due to safety regulations. |
| Used OEM | $75 - $200 |
| Remanufactured/Repair Service | $65 - $120 (You send your original part for rebuilding) |
| Shop Labor (Installation & SRS Reset) | $150 - $300 |
Frequently Asked Questions (FAQ)
Can I just reset the SRS light myself?
No. If the light is on due to a deployed pretensioner or a component fault, the SRS module has stored a hard code. This code cannot be cleared with a standard OBD-II scanner. The underlying fault must be repaired, and the module must be reset by a professional with specialized equipment.
🎬 Learn how to reset the SRS airbag light yourselfIs a slow retracting seat belt a safety hazard?
Yes. While it may seem like a minor annoyance, a belt that doesn't retract properly can create slack. In a collision, this slack can increase the distance your body travels forward before being restrained, increasing the risk of injury. It can also be a sign of a failing retractor mechanism.
What's the difference between the retractor and the buckle?
The retractor is the assembly inside the B-pillar that houses the belt spool and the pretensioner. The buckle is the receptacle on the side of the seat where you latch the belt's metal tongue. Some vehicles also have pretensioners in the buckle assembly, but the part discussed here is the main retractor unit.
Why can't I use a seat belt from a car that was in an accident?
Because the pretensioner is a one-time-use pyrotechnic device. Once it has been fired in a collision, it locks the belt and is no longer functional. It must be replaced. Infiniti's official position is that any seat belt assembly worn during a collision should be replaced.
Helpful Videos
Technical Specifications
OEM Part Numbers: 868425NA2A 868425NA9A 86843-5NA8A 868435NA9A 868435VS0A 868435VS8A 86884-9CN8A 868845NA8A 868845VS8A 868851BA0C 868855NA0A 868855NA8A 868855VS0A 868855VS8A
Contains a pyrotechnic (explosive) charge for the pretensioner function. System operates on a 12V DC circuit but is controlled by the SRS module. Resistance values for the pretensioner circuit are critical and monitored by the SRS module.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- INFINITI QX50:
- INFINITI QX55:
- Infiniti EX35:
- Infiniti EX37: