What Does B1901 Mean?
This code indicates the airbag control module has detected a short to ground condition in the feed or return circuit of crash sensor #1. The module continuously monitors voltage levels in crash sensor circuits, and when it detects an abnormally low voltage (shorted to ground), it sets this code and typically illuminates the airbag warning light. This fault prevents proper crash sensor operation and may disable the airbag system.
Safety Warning
Not safe to continue driving with this fault as the airbag system is likely disabled or operating improperly, meaning airbags may not deploy in a crash. This is a critical safety system failure requiring immediate attention and repair before normal vehicle operation.
Common Causes
45%
Damaged or chafed wiring harness causing short to ground in crash sensor #1 circuit
30%
Failed crash sensor #1 with internal short to ground
15%
Corroded or damaged connector at crash sensor #1 causing ground short
10%
Airbag control module internal failure or damaged connector pins
Diagnostic Steps
1
Step 1: Perform visual inspection of crash sensor #1 location (typically front bumper area) for physical damage, connector damage, or obvious wiring issues. Check for accident history or recent front-end repairs.
2
Step 2: Disconnect crash sensor #1 connector and inspect for corrosion, moisture, bent pins, or damage. Clean and apply dielectric grease if corrosion is present, then retest.
3
Step 3: With sensor disconnected, use a digital multimeter to measure resistance between each crash sensor circuit pin at the harness side and ground. Should read open circuit (infinite resistance); any continuity indicates a short to ground in the wiring.
4
Step 4: If wiring tests good, measure resistance across crash sensor terminals. Compare to manufacturer specifications (typically 1-5k ohms). Readings near 0 ohms indicate internal sensor short.
5
Step 5: Trace wiring harness from sensor to airbag module looking for pinch points, chafing against metal, or damage from previous repairs. Pay special attention to areas where harness routes near metal body components.
6
Step 6: After repairs, clear codes, cycle ignition, and verify airbag light extinguishes and code does not return. Perform airbag system self-test if available through scan tool.
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
This code indicates the airbag control module has detected a short to ground condition in the feed or return circuit of crash sensor #1. The module continuously monitors voltage levels in crash sensor circuits, and when it detects an abnormally low voltage (shorted to ground), it sets this code and ...
The most common cause of B1901 (Air Bag Crash Sensor #1 Feed/Return Circuit Short To Ground) is: Damaged or chafed wiring harness causing short to ground in crash sensor #1 circuit
Typical repair costs for B1901 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Not safe to continue driving with this fault as the airbag system is likely disabled or operating improperly, meaning airbags may not deploy in a crash. This is a critical safety system failure requiring immediate attention and repair before normal vehicle operation.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1901 to identify the root cause.
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Quick Info
Category
Body
System
Supplemental Restraint System (SRS/Airbag)
Difficulty
Type
Manufacturer
Recommended Tools
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