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Home / DTC / B1902 — Air Bag Crash Sensor #1 Ground Circuit Failure

B1902 — Air Bag Crash Sensor #1 Ground Circuit Failure

Detailed page for trouble code B1902.

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B1902

Other B — Body

Air Bag Crash Sensor #1 Ground Circuit Failure

Brand: Other
Type: B — Body
Views: UK: 13 EN: 48 RU: 20
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Page language: EN

Causes

  • Open or high-resistance ground connection between crash sensor and vehicle chassis or SRS module
  • Corroded, damaged, or loose ground strap or wiring harness
  • Faulty or contaminated sensor connector terminals (corrosion, bent pins, pushed-out terminal)
  • Damaged or chafed wiring with internal breaks or intermittent short to insulated wiring
  • Faulty crash sensor or SRS control module (less common)
  • Recent body repair or component replacement that disturbed the ground location

Symptoms

  • Illuminated SRS/airbag warning lamp on instrument cluster
  • Possible diagnostic trouble codes related to crash sensor or SRS circuits
  • Intermittent SRS lamp due to intermittent ground connection
  • Vehicle may fail SRS diagnostics; airbags may be disabled until repaired

What to check

  • Confirm SRS warning lamp behavior with ignition ON and during self-check
  • Retrieve all SRS codes and freeze-frame data with a capable scan tool
  • Visually inspect crash sensor, mounting, connector, and wiring harness for damage or corrosion
  • Inspect and clean ground points, ground straps and chassis mating surfaces
  • Check for recent service/bodywork in sensor area that could have loosened ground
  • Use a DVOM to check battery voltage and ensure stable supply to SRS system before testing

Signal parameters

  • Connector ground continuity to chassis: expected near 0 ohms (typically >5–10 ohms indicates problem
  • Ground terminal should show 0 V with respect to chassis ground when measured with DVOM
  • Sensor signal lines: no short to ground or B+ (no direct short); expected sensor output voltage varies by design and only changes during an event
  • SRS module supply voltage typically battery voltage (~12 V) with ignition ON; ensure supply present before deeper testing

Diagnostic algorithm

  1. Safety first: follow the manufacturer's SRS service procedure to disable the system before doing physical work. Typically remove negative battery terminal and wait the specified time (consult service literature).
  2. Connect a qualified scan tool with SRS capability. Read and record all stored and pending SRS codes and freeze frame data.
  3. Perform a careful visual inspection of Crash Sensor #1, its connector, and the harness route. Look for corrosion, bent pins, damaged insulation, pin-back terminals, or evidence of water intrusion.
  4. Inspect and clean the sensor ground and any nearby chassis ground stud. Remove oxidation and ensure a good metal-to-metal contact.
  5. With the battery reconnected and appropriate safety measures in place, check continuity between the sensor ground terminal and a known good chassis ground using a DVOM. Compare to expected values (near 0 ohms).
  6. Back-probe the sensor connector (or harness pins) and confirm ground is 0 V relative to chassis with ignition ON. Wiggle the harness to check for intermittent faults while watching the meter and scan tool for changes.
  7. If ground continuity is good, perform resistance checks of the sensor itself per manufacturer specs or substitute a known-good sensor if available to isolate sensor vs. wiring.
  8. If wiring shows open/high resistance or intermittent behavior, locate and repair the damaged section (repair or replace connector, splice, or wiring as required).
  9. After repairs, clear codes with the scan tool and perform SRS system self-test. Confirm code does not return and SRS warning lamp behavior is correct.
  10. If the code persists after wiring and ground verification, consider replacing the crash sensor or consult SRS module diagnostics per manufacturer procedure. Do not replace parts unless testing supports it.

Likely causes

  • Corroded ground terminal at crash sensor or nearby chassis ground stud
  • Broken ground wire at a harness flex point (under dash, under seat, or near mounting bolts)
  • Connector not fully seated or terminal backing-out after service
  • Water intrusion in connector causing high resistance ground
  • Aftermarket equipment or wiring tied into SRS ground causing poor connection

Fault status

⚠️ Status
Air Bag Crash Sensor #1 ground circuit open/high resistance detected — SRS lamp illuminated
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1900 B1901 B1903 B1920 B1600
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