What Does B1902 Mean?
This code indicates the airbag control module has detected a fault in the ground circuit for crash sensor #1, which is typically a front-impact or side-impact accelerometer. The airbag control module continuously monitors the integrity of all crash sensor circuits and has identified an open circuit, high resistance, or poor ground connection in the sensor's return path. This fault prevents the module from receiving accurate crash data from this sensor, compromising the airbag system's ability to deploy properly in a collision.
Safety Warning
This is a critical safety issue as the airbag system may not deploy properly or at all during a collision. The airbag warning light will be illuminated and the vehicle should not be driven until repaired, as occupant protection is severely compromised.
Common Causes
35%
Corroded or loose ground connection at crash sensor mounting point or ground splice
30%
Damaged or broken wiring in crash sensor ground circuit due to collision repair, water intrusion, or rodent damage
20%
Faulty crash sensor #1 with internal ground circuit failure
10%
Damaged or corroded connector at crash sensor or airbag control module
5%
Failed airbag control module with internal ground circuit fault
Diagnostic Steps
1
Step 1: Perform visual inspection of crash sensor #1 location (typically front bumper area or A-pillar) for physical damage, corrosion, or loose mounting. Check sensor mounting bolt for proper torque and clean metal-to-metal ground contact.
2
Step 2: Using a digital multimeter, measure resistance between crash sensor ground pin and known good chassis ground. Reading should be less than 1 ohm. If higher, trace ground wire back to splice or control module checking for breaks or corrosion.
3
Step 3: Disconnect crash sensor connector and inspect terminals for corrosion, bent pins, or water intrusion. Clean with electrical contact cleaner and check connector lock mechanism. Measure resistance of ground wire from sensor connector back to airbag control module (should be less than 5 ohms).
4
Step 4: If wiring and grounds test good, substitute a known-good crash sensor or measure sensor internal resistance per manufacturer specifications (typically 500-5000 ohms between signal and ground). Replace sensor if out of specification.
5
Step 5: Clear codes and perform airbag system self-test. Monitor live data for crash sensor #1 voltage readings (typically 2.5V at rest). Gently tap sensor mounting area to verify signal response. If fault returns immediately, suspect control module internal fault.
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
This code indicates the airbag control module has detected a fault in the ground circuit for crash sensor #1, which is typically a front-impact or side-impact accelerometer. The airbag control module continuously monitors the integrity of all crash sensor circuits and has identified an open circuit,...
The most common cause of B1902 (Air Bag Crash Sensor #1 Ground Circuit Failure) is: Corroded or loose ground connection at crash sensor mounting point or ground splice
Typical repair costs for B1902 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This is a critical safety issue as the airbag system may not deploy properly or at all during a collision. The airbag warning light will be illuminated and the vehicle should not be driven until repaired, as occupant protection is severely compromised.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1902 to identify the root cause.
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Quick Info
Category
Body
System
Supplemental Restraint System (Airbag)
Difficulty
Type
Manufacturer
Recommended Tools
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