If your OBD-II scanner displays B0055, your vehicle has detected an abnormal electrical resistance within the passenger seat belt pretensioner deployment loop. While your vehicle will continue to operate normally, this diagnostic trouble code (DTC) indicates that the Supplemental Restraint System (SRS) may not be able to properly tighten the passenger’s seat belt during a collision.
Seat belt pretensioners are one of the first safety devices activated in a crash. Before the airbags deploy, the Airbag Control Module (ACM) commands the pretensioner to rapidly remove slack from the seat belt, helping position the passenger correctly for maximum protection. If the ACM detects that the deployment loop resistance is outside of factory specifications, it stores B0055 and illuminates the Airbag Warning Light.
This guide explains what the B0055 code means, common symptoms, causes, repair costs, and how technicians properly diagnose the problem.
Quick Facts
| Item | Information |
|---|---|
| OBD-II Code | B0055 |
| Description | Passenger Seat Belt Pretensioner Deployment Loop Resistance (Subfault) |
| Category | Body (B) |
| System | Supplemental Restraint System (SRS) |
| Severity | ★★★★★ (Critical) |
| Safe to Drive? | Mechanically yes, safety-wise no |
| Repair Difficulty | Moderate |
| Typical Repair Cost | $150–$1,300 |
What Does B0055 Mean?
The B0055 diagnostic trouble code indicates the Airbag Control Module has detected an abnormal resistance value within the passenger seat belt pretensioner deployment loop.
Every pyrotechnic pretensioner contains a firing circuit with a carefully calibrated electrical resistance. During every ignition cycle, the ACM performs a self-test by measuring that resistance.
If the measured resistance is:
- Too high
- Too low
- Intermittent
- Completely open
the ACM stores B0055 and disables the affected pretensioner until repairs are completed.
Unlike deployment control codes that indicate general circuit faults, B0055 specifically identifies an out-of-spec resistance value.
Symptoms of B0055
Common symptoms include:
- Airbag warning light illuminated
- “Service Airbag” message
- SRS warning indicator
- Stored B0055 code
- Passenger restraint system warning
- Additional SRS codes
- No drivability problems
The pretensioner only activates during a collision, so most drivers notice no changes while driving.
Common Causes
1. Failed Passenger Pretensioner
Internal damage to the pretensioner can change the firing circuit resistance beyond acceptable limits.
2. Damaged Under-Seat Wiring
Passenger seat movement can damage the harness through:
- Broken wires
- Pinched conductors
- Chafed insulation
- Stretched wiring
3. Loose SRS Connector
Yellow SRS connectors beneath the passenger seat may loosen after:
- Seat removal
- Carpet replacement
- Interior repairs
- Aftermarket accessory installation
Even a small increase in resistance can trigger B0055.
4. Corroded Electrical Terminals
Moisture beneath the carpet can corrode connectors and increase circuit resistance.
5. Previous Collision Repairs
Improper repairs after an accident may leave:
- Reused pretensioners
- Damaged wiring
- Incorrect splices
- Poor-quality replacement parts
6. Airbag Control Module Failure
Although uncommon, a defective ACM can incorrectly report resistance faults.
How Serious Is B0055?
Extremely serious.
The passenger seat belt will continue functioning normally, but the pretensioner may fail to activate during a collision.
Without proper pretensioner operation:
- Seat belt slack remains
- Passenger movement increases
- Airbag effectiveness is reduced
- Injury risk increases
Can You Drive With B0055?
Technically yes.
Should you?
No.
While the vehicle remains mechanically safe, the SRS may not provide the level of protection the manufacturer intended during an accident.
How to Diagnose B0055
Step 1: Scan the SRS Module
Use a professional scan tool capable of reading:
- Supplemental Restraint System
- Airbag Module
- Body Control Module
Generic OBD-II readers usually cannot retrieve B-codes.
Step 2: Inspect Passenger Seat Wiring
Inspect beneath the passenger seat for:
- Loose connectors
- Broken wires
- Pinched harnesses
- Corrosion
Move the seat through its complete adjustment range while checking the wiring.
Step 3: Check for Related Codes
B0055 frequently appears alongside:
- B0051
- B0052
- B0054
- B0022
- B0033
Multiple SRS faults often indicate shared wiring or ACM problems.
Step 4: Measure Deployment Loop Resistance
Using factory service information, verify pretensioner circuit resistance.
Never probe an SRS circuit with a powered test light or jumper wire.
Step 5: Inspect the Pretensioner Assembly
Check for:
- Previous deployment
- Physical damage
- Retractor problems
- Water intrusion
Replace any deployed pretensioner assembly.
Common Repair Solutions
| Repair | Estimated Cost |
|---|---|
| Repair seat wiring | $150–350 |
| Replace SRS connector | $100–250 |
| Replace passenger pretensioner | $350–900 |
| Replace seat wiring harness | $300–700 |
| Replace Airbag Control Module | $900–2,000 |
Common Diagnostic Mistakes
A common mistake is replacing the pretensioner without first inspecting the wiring.
Many B0055 faults are actually caused by:
- Corroded connectors
- Loose terminals
- Damaged harnesses
- Pinched wiring beneath the seat
Always verify circuit integrity before replacing expensive SRS components.
Vehicles That Commonly Experience B0055
B0055 may appear on vehicles including:
- Chevrolet Silverado
- Chevrolet Tahoe
- GMC Sierra
- GMC Yukon
- Cadillac Escalade
- Ford F-150
- Ford Explorer
- Toyota Camry
- Toyota Highlander
- Honda Accord
- Honda CR-V
- Acura RDX
- Nissan Altima
- Hyundai Santa Fe
- Kia Sorento
Manufacturer-specific definitions may vary.
How to Prevent B0055
Although some failures are unavoidable, you can reduce the risk by:
- Avoiding damage to under-seat wiring
- Keeping carpets dry
- Disconnecting the battery before removing seats
- Replacing deployed pretensioners after collisions
- Using OEM replacement parts
- Addressing airbag warning lights immediately
Frequently Asked Questions
What causes B0055?
The most common causes include a failed passenger pretensioner, damaged wiring, loose SRS connectors, corrosion, previous collision repairs, or Airbag Control Module failure.
What does deployment loop resistance mean?
It refers to the total electrical resistance measured through the pretensioner’s firing circuit. If resistance falls outside factory specifications, the ACM stores B0055.
Is B0055 dangerous?
Yes.
The passenger pretensioner may fail during a collision, reducing the effectiveness of the entire restraint system.
Can I clear B0055?
Yes, but unless the underlying fault is repaired, the code will return during the next SRS self-test.
Does B0055 always require a new pretensioner?
No.
Many repairs involve damaged wiring or poor electrical connections rather than replacing the pretensioner itself.
Will B0055 affect normal driving?
No.
The code affects only the Supplemental Restraint System and does not impact engine or transmission operation.
Final Thoughts
The B0055 code indicates that the passenger seat belt pretensioner deployment loop resistance is outside of factory specifications. While the vehicle may continue driving without noticeable symptoms, the passenger restraint system may not perform correctly during a collision.
Fortunately, many B0055 repairs involve fixing damaged wiring, cleaning corroded connectors, or repairing the under-seat harness rather than replacing expensive SRS components. Proper diagnosis is essential to restoring the full protection of your vehicle’s restraint system.
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