B1909: Crash Sensor #2 Ground Short
The B1909 code indicates that the Restraint Control Module (RCM) has detected a short to ground in the reference circuit of the number 2 impact (satellite) sensor. This sensor, typically located on the side or front of the vehicle, provides acceleration data to the RCM to determine crash severity. A short to ground in its reference line prevents proper communication or sensor reference voltage.
1. Commonly Affected Makes
2. Most Common Causes
- Wiring for crash sensor #2 shorted to ground (chassis/body)
- Internal short in crash sensor #2
- Damaged, corroded, or pushed-back terminals in the sensor connector
- Faulty RCM with internal driver circuit short
3. Symptoms You Will Notice
- Airbag warning light illuminated
- Supplemental Restraint System (SRS) fault stored
4. Step-by-Step Diagnosis
Scan the RCM for B1909 and any related codes.
Visually inspect the crash sensor #2 connector and wiring for damage, corrosion, or shorts to ground.
Disconnect the sensor and measure resistance between the reference circuit and ground; a low reading indicates a short.
If wiring is okay, replace crash sensor #2 and clear codes.
If the code returns, test the RCM by substituting a known-good module.
5. Frequently Asked Questions
Is it safe to drive?▼
No, the airbag system may be disabled, increasing injury risk in a crash. Have the vehicle towed to a repair shop.
How much does it cost to fix?▼
Typically $150–$400, including diagnosis ($50–$100) and sensor replacement ($100–$300). RCM replacement can exceed $800.