What Does B1999 Mean?
This code indicates the airbag control module has detected abnormally low electrical resistance in the passenger side-mounted airbag squib circuit. The squib is the pyrotechnic initiator that deploys the airbag, and low resistance typically means a short circuit or compromised wiring in the deployment circuit. The airbag control module continuously monitors resistance values to ensure the system is ready for deployment, and values outside normal range (typically 2-3 ohms) trigger this fault.
Safety Warning
Do not drive the vehicle. The passenger side airbag may deploy unexpectedly due to the short circuit, or may fail to deploy in a crash. This is a serious safety hazard requiring immediate professional repair at a qualified facility.
Common Causes
45%
Damaged or shorted wiring harness between airbag control module and passenger seat side airbag connector, often from seat track movement or previous repairs
30%
Failed passenger side seat-mounted airbag module with internal squib short circuit
15%
Corroded or moisture-contaminated clock spring or seat harness connector creating short to ground
10%
Faulty airbag control module incorrectly reading squib resistance values
Diagnostic Steps
1
Step 1: Disconnect battery negative terminal and wait 10 minutes for airbag system capacitor discharge. Visually inspect passenger seat wiring harness and connectors for damage, chafing, exposed wires, or corrosion at connection points under seat
2
Step 2: Using digital multimeter in ohms mode, measure squib resistance at disconnected passenger side airbag connector (measure across squib terminals only, not to ground). Verify reading is within manufacturer specification, typically 2.0-3.5 ohms. Reading near zero ohms confirms short circuit
3
Step 3: If squib resistance is normal, inspect and measure resistance through wiring harness from airbag module connector to control module connector. Look for resistance below 5 ohms to ground on either squib wire, indicating harness short
4
Step 4: If wiring harness tests normal, suspect faulty airbag module. Replace passenger side seat airbag assembly if squib shows low resistance. If all components test normal, replace airbag control module
5
Step 5: After repairs, reconnect battery, clear codes, and perform airbag system self-test. Verify code does not return and airbag warning light extinguishes properly
Estimated Repair Cost
$300 - $1,500
Parts + labor, varies by vehicle and location
This code indicates the airbag control module has detected abnormally low electrical resistance in the passenger side-mounted airbag squib circuit. The squib is the pyrotechnic initiator that deploys the airbag, and low resistance typically means a short circuit or compromised wiring in the deployme...
The most common cause of B1999 (Passenger Sid, Side mount Airbag Low resistance on Squib) is: Damaged or shorted wiring harness between airbag control module and passenger seat side airbag connector, often from seat track movement or previous repairs
Typical repair costs for B1999 range from $300 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Do not drive the vehicle. The passenger side airbag may deploy unexpectedly due to the short circuit, or may fail to deploy in a crash. This is a serious safety hazard requiring immediate professional repair at a qualified facility.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1999 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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