B1931

Code

Other B — Body

Air Bag Crash Sensor #1 Feed/Return Circuit Failure

Brand: Other

Type: B — Body

Views: UK: 23 EN: 46 RU: 41

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Page language: EN

Causes

Open or short in the crash sensor supply or return wiring
Corroded, loose, or damaged connector at the sensor or SRS control module
Faulty crash (impact) sensor
Poor ground or low battery voltage affecting sensor circuit
Intermittent connection caused by pin push-out, bent terminal, or chafed wire
Faulty SRS (airbag) control module or internal driver circuit

Symptoms

SRS/Airbag warning lamp illuminated or flashing on instrument panel
Possible disabling of airbag deployment for affected circuit
Stored SRS-related trouble codes (B1931 plus others)
No crash-related deployment (in non-crash condition) — typically no drivability symptoms

What to check

Obtain full SRS code list and freeze frame with a compatible scan tool
Visually inspect sensor #1 connector and wiring for damage, corrosion, bent pins, or moisture
Check related connectors at the SRS control module for secure fit and corrosion
Verify battery voltage and ground integrity before and during testing
Backprobe the sensor connector while following safety precautions to monitor signal voltages
Perform continuity/resistance checks between the sensor connector and the SRS module harness connector

Signal parameters

Reference/supply voltage typically around 5 V (manufacturer-dependent) when ignition ON — verify on vehicle wiring diagram
Sensor return/ground should be near 0 V with ignition ON (quiescent state) and change only during a commanded event
Continuity between sensor terminal and module terminal: low ohms (near 0 Ω to low single-digit ohms) — open or very high resistance indicates a break
Open-circuit condition typically >10 kΩ or OL on an ohmmeter
Intermittent or fluctuating voltage on feed/return is a sign of poor connection or broken wire

Diagnostic algorithm

Safety first: Disable the SRS system per manufacturer procedure (disconnect negative battery and wait the recommended time, or follow vehicle-specific SRS disable steps). Use proper ESD precautions and do not probe airbag squibs with high voltage.
Use a capable scan tool to confirm B1931 and record any additional SRS or CAN bus codes and freeze-frame data.
Visually inspect the wiring and connector for Crash Sensor #1 (look for chafe, pin damage, corrosion, moisture intrusion). Repair damage as required.
Reconnect battery (if required for tests) and backprobe the sensor supply and return circuits with ignition ON to verify reference voltage and ground. Compare readings to manufacturer specs.
With ignition OFF, measure continuity/resistance from sensor connector terminals to the SRS module harness connector to identify opens or high resistance. Wiggle harness while monitoring for intermittent changes.
If wiring and connectors check good, swap or bench-test the crash sensor per manufacturer procedure (some sensors are non-serviceable — consult service information). Replace sensor if it fails bench tests or swap reveals code clears.
If sensor and wiring are good, follow module-level diagnostics: check for internal driver faults or replace/repair the SRS control module per manufacturer guidance.
After repairs, clear codes, perform a full SRS system scan, and verify the SRS warning lamp extinguishes and no new related codes return. Verify proper operation per service procedures.

Likely causes

Damaged wiring harness between sensor #1 and SRS module (abrasion, chafe, connector damage)
Corroded or poorly seated connector at the sensor
Failed crash sensor #1
Intermittent contact in connector or at module pin

Fault status

⚠️ Status

Crash sensor #1 feed/return circuit failure — circuit open, short, high resistance or intermittent connection detected between sensor #1 and the SRS control module. SRS lamp illuminated.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours