B1901 — Air Bag Crash Sensor #1 Feed/Return Circuit Short To Ground

body electrical

Is it safe to drive?

Drive with caution The car drives normally, but with the SRS light on the airbags may not deploy in a crash. Treat it as a safety-critical repair: fine to drive to the shop, not fine to ignore for months.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm B1901 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many B0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the airbag / restraint system (SRS) for damage, corrosion, chafing or poor contact.
Subsystem check Read the SRS module with a scanner that supports airbag systems — generic OBD2 readers cannot see these codes.
Subsystem check Inspect under-seat connectors — they are often disturbed by seat movement or cleaning.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm B1901 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for B1901 (parts and labor, USD, independent shop rates): Reconnect or repair SRS wiring/connectors: $80–$250; SRS module reset or replacement: $300–$1,000; Replace a sensor or clockspring: $150–$500. Overall, fixing B1901 usually costs between $80 and $1,000. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

Will B1901 clear itself?

Sometimes B1901 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

How much does it cost to fix B1901?

Reconnect or repair SRS wiring/connectors — $80–$250; SRS module reset or replacement — $300–$1,000; Replace a sensor or clockspring — $150–$500. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

What does OBD2 code B1901 mean?

Air Bag Crash Sensor #1 Feed/Return Circuit Short To Ground (B1901): a body electrical fault affecting the airbag / restraint system (SRS). Short, gentle driving to a shop is usually possible. Most often caused by damaged wiring under seats or in the steering column, failed clockspring (driver airbag circuit), SRS control module fault or stored crash data.

What is the most common cause of B1901?

The most common causes are: damaged wiring under seats or in the steering column, failed clockspring (driver airbag circuit), SRS control module fault or stored crash data.

Is it safe to drive with B1901?

The car drives normally, but with the SRS light on the airbags may not deploy in a crash. Treat it as a safety-critical repair: fine to drive to the shop, not fine to ignore for months.

When your vehicle's onboard diagnostics detect that the feed or return circuit for the primary crash sensor is shorted to ground, the system stores trouble code B1901. This fault belongs to the supplemental restraint system (SRS), which manages airbags and related safety components. The crash sensor in question is typically the first sensor responsible for detecting a collision and signaling the module to deploy protective measures.

The SRS module constantly monitors the resistance and voltage patterns within its network of sensors, wiring, and connectors. When a short to ground appears in the feed or return circuit—meaning an unintended electrical path to the vehicle chassis has formed—the module recognizes this as an abnormal condition. Depending on your vehicle, the module may need to observe this condition across multiple drive cycles before confirming and storing B1901. It also captures a freeze frame snapshot, recording engine speed, load, coolant temperature, and vehicle speed at the exact moment the fault first appeared. Reviewing this data helps pinpoint whether the issue occurred under specific driving conditions or environmental factors.

Once B1901 is logged, the SRS module disables the airbag system as a safety precaution. A deployed airbag during a circuit fault could cause injury or fail to deploy when actually needed. Understanding this code and its implications is essential for any vehicle owner—ignoring it leaves occupants without critical crash protection.

Symptoms of B1901

The airbag warning lamp remains illuminated on the dashboard
The instrument cluster may display an airbag system disabled notification
No changes to normal driving behavior—steering, braking, and acceleration feel unchanged
In some vehicles, a chime or alert tone sounds when the fault is first detected
Certain models may store additional SRS-related trouble codes alongside B1901
Seatbelt pretensioners could be deactivated along with the airbags

Common Causes of B1901

Low or depleted backup battery supplying the SRS module, causing voltage irregularities
Failure of the clockspring—a rotating electrical connector within the steering column that carries signals to the driver's airbag
Wiring damage under the front seats, often from repeated seat adjustment, cargo movement, or moisture intrusion
Corrosion or poor contact at the crash sensor connector or module harness
Faulty impact sensor unable to maintain proper circuit resistance
Wiring chafing or melting near heat sources such as the exhaust manifold or engine block
Aftermarket accessory installation that interfered with SRS wiring circuits

How to Diagnose B1901

Connect a compatible OBD2 scanner capable of reading manufacturer-specific SRS codes, confirm B1901 is present, and record the freeze frame data. This snapshot reveals what the engine was doing when the fault occurred.
Pull all stored trouble codes—not just B1901. Related codes often point to the specific circuit or component that failed. Also check for any technical service bulletins (TSBs) applicable to your make and model by searching the manufacturer's website or the NHTSA database.
Perform a thorough visual inspection of SRS wiring, particularly in areas prone to movement or heat exposure. Check under both front seats, inside the steering column, and at the crash sensor locations. Look for cracked insulation, exposed conductors, or connectors that are not fully seated.
Test system voltage and ground connections at the SRS module. A weak battery or unstable charging system can trigger false shorts that clear once voltage normalizes.
If the clockspring is suspected, verify its resistance values against factory specifications. A faulty clockspring often causes intermittent airbag warnings that come and go.
Clear the code and perform a complete drive cycle, including hard stops if safely possible, to replicate the freeze frame conditions. If B1901 returns, the short to ground is confirmed and requires component-level repair.

Repair Options and Costs

The appropriate fix for B1901 depends on which part of the circuit is actually damaged. Simple wiring repairs tend to be the most common solution.

Repair or reconnect damaged SRS wiring and connectors: parts and labor typically run $80 to $250
SRS module reset by a dealer or replacement with a new or refurbished unit: $300 to $1,000 depending on make and model
Replace a faulty crash sensor, impact sensor, or clockspring: $150 to $500 for parts and installation

Total Cost to Fix B1901

Most repairs for B1901 fall between $80 and $1,000 when using independent repair shops in the United States. The wide range reflects how different vehicles and failure points affect the final bill. Diagnosing before purchasing parts is strongly recommended—the cheapest possible fix (a loose connector or minor wire repair) is far more common than needing a full module replacement.

Can You Drive with B1901?

Your vehicle will handle and drive exactly as it normally would with B1901 stored. However, the airbag system will be disabled or partially disabled until the fault is resolved. In a collision, the airbags may not deploy, significantly increasing the risk of injury. Treat this as a safety-critical issue: it is reasonable to drive directly to a trusted repair shop, but it should not be ignored or left unaddressed for an extended period.