B1931 — Air Bag Crash Sensor #1 Feed/Return Circuit Failure

OBD2 code B1931 flags a problem with the airbag / restraint system (SRS) (air bag crash sensor #1 feed/return circuit failure). Short, gentle driving to a shop is usually possible. Common culprits: damaged wiring under seats or in the steering column, SRS control module fault or stored crash data, failed clockspring (driver airbag circuit).

body electrical

Is it safe to drive?

Drive with caution The car drives normally, but with the SRS light on the airbags may not deploy in a crash. Treat it as a safety-critical repair: fine to drive to the shop, not fine to ignore for months.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm B1931 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many B0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the airbag / restraint system (SRS) for damage, corrosion, chafing or poor contact.
Subsystem check Read the SRS module with a scanner that supports airbag systems — generic OBD2 readers cannot see these codes.
Subsystem check Inspect under-seat connectors — they are often disturbed by seat movement or cleaning.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm B1931 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for B1931 (parts and labor, USD, independent shop rates): Reconnect or repair SRS wiring/connectors: $80–$250; Replace a sensor or clockspring: $150–$500; SRS module reset or replacement: $300–$1,000. Overall, fixing B1931 usually costs between $80 and $1,000. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

What does OBD2 code B1931 mean?

How much does it cost to fix B1931?

Reconnect or repair SRS wiring/connectors — $80–$250; Replace a sensor or clockspring — $150–$500; SRS module reset or replacement — $300–$1,000. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

What is the most common cause of B1931?

The most common causes are: damaged wiring under seats or in the steering column, SRS control module fault or stored crash data, failed clockspring (driver airbag circuit).

How do I diagnose B1931 myself?

Start with a scan: confirm B1931, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the air bag crash sensor #1 feed/return circuit, and verify the suspect component against live data before buying parts.

Is it safe to drive with B1931?

The car drives normally, but with the SRS light on the airbags may not deploy in a crash. Treat it as a safety-critical repair: fine to drive to the shop, not fine to ignore for months.

When the powertrain control module stores trouble code B1931, it means the onboard computer has detected a problem with the supplemental restraint system's primary crash sensor wiring. Specifically, the fault involves the feed and return circuit for air bag crash sensor number one. This diagnostic code lives in the body electrical category of OBD2 trouble codes, which covers systems beyond the engine and transmission.

The restraint system module does not set B1931 based on a single glitch. It requires the fault condition to appear repeatedly under specific driving or ambient conditions before the module decides the problem is genuine and turns on the warning light. When technicians retrieve this code, they also pull the associated freeze frame data—snapshot information showing engine load, RPM, coolant temperature, and vehicle speed at the exact moment the fault was detected. This data proves invaluable when you need to replicate the conditions that trigger the problem during testing.

The air bag system relies on crash sensors positioned throughout the vehicle to detect impact severity and signal the control module when deployment is warranted. These sensors communicate through dedicated wiring circuits that carry both power and signal information. When this communication pathway breaks down—whether through wiring damage, connector problems, or component failure—the module logs B1931 and illuminates the air bag warning lamp to alert the driver that the safety system may not function correctly in a collision.

Symptoms of B1931

Supplemental restraint system warning lamp stays illuminated on the instrument cluster
Air bag status message appears in the driver information center or dashboard display
No noticeable changes to vehicle drivability, steering, braking, or acceleration
In some cases, the system displays a message indicating that airbags are disabled
Other diagnostic codes may accompany B1931, particularly related to sensor or module faults
The seatbelt pretensioner system may also show reduced functionality depending on the specific fault
Symptoms remain constant regardless of weather or road conditions

Common Causes

Corroded, damaged, or loose wiring connectors at the crash sensor or module
Depleted backup battery or consistently low system voltage affecting the SRS circuit
Stored crash data or module internal fault within the supplemental restraint computer
Failed clockspring assembly, which carries the electrical connection to the driver's air bag
Faulty front or side impact sensor triggering incorrect readings in the circuit
Under-seat wiring harnesses damaged by seat track movement or cargo shifting
Poor ground connection at the restraint system module

How to Diagnose B1931

Connect an appropriate OBD2 scanner and confirm that B1931 is stored in the system. Save all freeze frame data before clearing anything—this record shows exactly what conditions were present when the module first detected the fault.
Pull all related diagnostic trouble codes from the air bag system. Codes in the B1900 series frequently appear alongside B1931 and point toward specific circuit problems such as shorts to ground or battery. Review manufacturer technical service bulletins for your vehicle year, make, and model—many restraint system codes have documented factory solutions or software recalibrations available through the manufacturer database or NHTSA website.
Perform a thorough visual inspection of the SRS wiring harness, focusing on connectors leading to the crash sensors and control module. Look for chafed insulation, bent pins, corrosion buildup, or connectors that are not fully seated. Pay particular attention to under-seat wiring, which often sustains damage from repeated seat adjustment or routine cleaning.
Access the restraint system module with a scanner capable of reading air bag diagnostic data. Generic OBD2 code readers cannot communicate with supplemental restraint systems—you need a manufacturer-specific tool or professional-grade diagnostic scanner that supports SRS modules. Read live data streams from the crash sensors to verify they report reasonable values when the vehicle is stationary.
Check system voltage and verify that the backup battery—common in many restraint modules—is holding a proper charge. Low voltage at the module can cause intermittent circuit faults that mimic hard wiring problems.
After completing repairs or replacements, clear the code and perform a complete drive cycle that recreates the conditions recorded in the freeze frame data. Confirm that B1931 does not return after several ignition cycles under similar conditions.

Repair Options and Costs

Reconnect or repair SRS wiring and connectors: $80–$250. Most inexpensive scenario involves fixing damaged harness sections, cleaning corroded terminals, or reseating loose connectors. This work typically requires an hour or less of labor at standard shop rates.

Replace a crash sensor or clockspring: $150–$500. If inspection reveals a failed impact sensor or broken clockspring spiral assembly, parts and installation fall within this range. Clockspring replacement often requires steering wheel removal, which adds to labor time.

SRS module reset or replacement: $300–$1,000. Module replacement becomes necessary when internal circuitry fails or when crash data stored in memory prevents normal operation. Some modules can be reset and recertified by specialty shops, which sometimes reduces cost compared to buying a new unit.

Total cost assessment: Most B1931 repairs finish between $80 and $1,000 depending on which component is responsible. An accurate diagnosis before purchasing parts always saves money—the most expensive repair option is rarely the first one to consider.

Driving Safety Verdict

A vehicle with B1931 stored will continue to drive, accelerate, and brake normally. However, the illuminated air bag warning lamp indicates that the supplemental restraint system may not deploy during a crash. Treat this as a safety-critical issue requiring prompt professional attention. Driving the car to a repair facility is acceptable, but leaving this problem unaddressed for months puts occupants at significant risk in any collision scenario.