What Does B2118 Mean?
This code indicates the Airbag Control Module (ACM) has detected abnormally low electrical capacitance in the passenger side-mounted airbag squib circuit. The squib is the electrical igniter that deploys the airbag, and low capacitance suggests an open circuit, damaged wiring, or faulty squib. This fault prevents proper airbag deployment and typically illuminates the airbag warning light on the dashboard.
Safety Warning
The vehicle is technically drivable but the passenger side airbag will NOT deploy in a collision, significantly increasing injury risk to passengers. This repair should be completed immediately before carrying passengers, as the vehicle's primary safety system is compromised.
Common Causes
35%
Damaged or broken wiring in the passenger seat side airbag harness, often caused by seat movement wear or previous seat removal
30%
Faulty passenger side-mounted airbag squib or airbag module itself requiring replacement
20%
Corroded or loose electrical connector at the passenger side airbag module or under the seat
10%
Failed Airbag Control Module (ACM) misreading squib resistance or capacitance values
5%
Open circuit in wiring between ACM and passenger side airbag due to chafing or damage
Diagnostic Steps
1
Step 1: Perform visual inspection of passenger seat side airbag wiring harness, checking for obvious damage, chafing, cuts, or signs of previous repair. Pay special attention to wiring at seat track pivot points where movement occurs.
2
Step 2: Disconnect passenger side airbag connector (with battery disconnected and wait 10+ minutes). Inspect connector terminals for corrosion, bent pins, or moisture intrusion. Clean and apply dielectric grease if corroded.
3
Step 3: Using a multimeter set to resistance mode, measure squib resistance across the airbag connector terminals. Expected reading should be between 2-3 ohms (consult vehicle-specific specs). Reading of OL (open) or significantly higher indicates faulty squib or open circuit.
4
Step 4: If squib resistance is correct, check continuity of wiring from ACM connector to passenger seat airbag connector using wiring diagram. Test both wires for opens and shorts to ground. Repair or replace harness as needed.
5
Step 5: If all wiring and squib tests are within specification, suspect faulty ACM. Clear codes, reconnect all components, and retest. If code returns immediately with known-good components, replace ACM.
6
Step 6: After repair, clear codes, perform airbag system self-test using scan tool, and verify airbag warning light extinguishes. Test drive and rescan to confirm no code return.
Estimated Repair Cost
$200 - $1,500
Parts + labor, varies by vehicle and location
This code indicates the Airbag Control Module (ACM) has detected abnormally low electrical capacitance in the passenger side-mounted airbag squib circuit. The squib is the electrical igniter that deploys the airbag, and low capacitance suggests an open circuit, damaged wiring, or faulty squib. This ...
The most common cause of B2118 (Passenger Sid, Side mount Airbag Low capacitance on Squib) is: Damaged or broken wiring in the passenger seat side airbag harness, often caused by seat movement wear or previous seat removal
Typical repair costs for B2118 range from $200 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle is technically drivable but the passenger side airbag will NOT deploy in a collision, significantly increasing injury risk to passengers. This repair should be completed immediately before carrying passengers, as the vehicle's primary safety system is compromised.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2118 to identify the root cause.
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Quick Info
Category
Body
System
Supplemental Restraint System (SRS/Airbag)
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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