B1907 — Air Bag Crash Sensor #2 Ground Circuit Failure #

Note: The code description may vary depending on the vehicle manufacturer.

• B1907: Air Bag Crash Sensor #2 Ground Circuit Failure (Ford, Lincoln, Mercury)
• B1907: Side Airbag Sensor #2 Ground Circuit Malfunction (Mazda)
• B1907: Crash Sensor 2 Ground Open (Jaguar)

Summary of Code B1907 #

B1907 is a diagnostic trouble code (DTC) that points to a problem with the ground circuit of the second crash sensor in your vehicle’s airbag system. The crash sensor, sometimes referred to as an impact or collision sensor, is essential for detecting sudden impacts and triggering airbag deployment. When the vehicle’s airbag control module (also called the Supplemental Restraint System Control Module or SRS module) detects an abnormal voltage or resistance in the ground circuit for sensor #2, it registers this code. This issue can compromise the airbag system’s ability to function correctly in an accident, putting occupant safety at risk. It’s a code that should never be overlooked, even if no obvious symptoms are present.

Common Symptoms for Code B1907 #

When B1907 is present, symptoms may be subtle or quite noticeable. Often, the only sign is a warning indicator on your dashboard. However, because this code signals a fault in a critical safety component, it’s important not to ignore any changes in your vehicle’s behavior. Typical symptoms include:

• Illuminated airbag warning light (SRS indicator stays on or flashes)
• Airbag system disabled or “Airbag OFF” message
• Diagnostic scanner unable to communicate with one or more airbag sensors
• Possible error messages related to “crash sensor” or “restraint system malfunction”
• No physical or driveability symptoms in most cases

Most Likely Causes for Code B1907 #

B1907 is usually triggered by electrical issues related to the crash sensor’s ground path. The ground circuit allows electricity to return to the vehicle’s battery negative terminal, completing the electrical circuit for the airbag sensor to work properly. If this circuit is interrupted or has too much resistance, the sensor can’t communicate with the SRS module. The most common causes, in order of frequency, are:

1. Corroded or loose ground connection for crash sensor #2
2. Damaged wiring harness (broken, frayed, or shorted wires leading to or from the sensor)
3. Faulty crash sensor #2 (internal sensor failure)
4. Poor connector fit or contamination at the sensor harness plug
5. Faulty SRS control module (rare, but possible if other codes are present)

Step-by-Step Diagnostic Process for Code B1907 #

Diagnosing B1907 requires a careful, methodical approach to ensure the airbag system remains safe and functional throughout the process. Always disconnect the battery and wait at least 10 minutes before working on any SRS components to avoid accidental deployment. Here’s a proven step-by-step method:

• Scan for codes: Use an OBD-II/EOBD scanner capable of reading SRS codes to confirm B1907 and check for related codes.
• Visual inspection: Locate crash sensor #2 (consult OEM repair manual for exact location) and inspect its ground wire, connectors, and the surrounding harness for corrosion, damage, or loose connections.
• Check ground integrity: Using a multimeter, measure resistance between the sensor ground terminal and chassis ground. Resistance should be near zero (< 0.1 ohm).
• Check for open/short circuits: Wiggle-test the harness while monitoring the multimeter or scanner for intermittent faults.
• Test the sensor: If wiring and ground check out, replace crash sensor #2 with a known good unit or test per OEM procedure.
• Test the SRS module: As a last resort, verify SRS module outputs and grounds, especially if multiple SRS codes are present.
• Clear codes and retest: After repairs, clear the code and drive the vehicle to confirm the issue is resolved.

Possible Repairs for Code B1907 #

Repairing B1907 focuses on restoring the integrity of the ground circuit for crash sensor #2. Your specific repair will depend on what the diagnostic process uncovers, but the most common solutions include:

• Clean and tighten the ground connection at crash sensor #2
• Repair or replace the wiring harness if wires are damaged or corroded
• Replace crash sensor #2 if it fails tests or shows obvious physical damage
• Replace or repair connectors that are loose, corroded, or water-damaged
• Replace the SRS control module only if all other components test good and the module is confirmed faulty

Is It Safe to Drive with Code B1907? #

No, it is not safe to drive with code B1907 present. While your vehicle will likely operate normally, the airbag system may be partially or completely disabled, leaving you and your passengers unprotected in the event of a collision. Some vehicles may even turn off all airbags if one sensor circuit is compromised. Always prioritize having this code diagnosed and repaired by a qualified technician as soon as possible. In emergencies, drive only to a service facility and avoid unnecessary trips.

Vehicles Most Commonly Affected by Code B1907 #

B1907 is most frequently reported in vehicles from manufacturers that use this specific code structure, particularly:

• Ford (Focus, F-150, Fusion, Explorer)
• Lincoln (MKX, Town Car)
• Mercury (Grand Marquis, Sable)
• Mazda (Mazda 3, Mazda 6, Tribute)
• Jaguar (various models using Ford-based SRS electronics)

Always consult your OEM service information, as code definitions and sensor locations may vary.

Common Mistakes & Best Practices for Code B1907 #

When dealing with SRS codes like B1907, mistakes can be costly—not just financially, but in terms of your safety. Here are errors to avoid and tips to ensure a successful repair:

• Attempting repairs without disconnecting the battery and waiting for SRS capacitors to discharge
• Ignoring connector corrosion or loose pins—these are a very common cause
• Replacing the crash sensor before thoroughly checking wiring and grounds
• Using generic scan tools that may not read all SRS codes or freeze frame data
• Skipping the final step of clearing codes and checking for immediate reappearance

Quick FAQ for Code B1907 #

Even experienced technicians and vehicle owners have questions about airbag codes. Here are answers to the most common:

• Q: Can a weak battery cause B1907?
• A: While a weak battery can trigger some airbag codes, B1907 specifically indicates a problem in the crash sensor’s ground circuit. Always check battery health, but focus on the sensor wiring and connections.
• Q: Is it safe to reset the code without fixing the issue?
• A: No. Clearing the code without addressing the root cause may temporarily extinguish the warning light, but your airbag system will still be compromised—and the code will return.