What Does B1938 Mean?
This code indicates that the airbag control module has detected an abnormal electrical short to ground in the passenger-side airbag circuit. The airbag control module continuously monitors the resistance and continuity of all airbag circuits, and when it detects lower than expected resistance (typically indicating a direct path to ground), it sets this fault code and typically disables the passenger airbag. This is a safety-critical fault that prevents proper deployment of the passenger airbag in a collision.
Safety Warning
This is a critical safety fault that typically disables the passenger airbag entirely, meaning the airbag will not deploy in a collision and puts the passenger at severe risk of injury. The vehicle should not be driven with passengers until this fault is repaired, and diagnosis should be performed immediately by a qualified technician due to the risk of accidental deployment during improper handling.
Common Causes
35%
Damaged or chafed wiring harness under passenger seat or in door pillar causing wire insulation to contact ground
30%
Faulty passenger airbag squib or internal short within the airbag module itself
20%
Corroded or damaged airbag connector at the passenger airbag module or under seat
10%
Failed airbag control module with internal circuit fault misinterpreting normal resistance as a short
5%
Damaged clockspring or wiring connections if passenger airbag circuit routes through steering column area
Diagnostic Steps
1
Step 1: Perform visual inspection of all accessible wiring and connectors in the passenger airbag circuit, especially under the passenger seat, along the seat tracks, and near the dashboard. Look for crushed, chafed, or damaged wiring that may be contacting metal frames or brackets.
2
Step 2: Disconnect the negative battery cable and wait 10 minutes for capacitor discharge. Then disconnect the passenger airbag connector and measure resistance from both airbag squib terminals to vehicle ground using a digital multimeter. Normal reading should be infinite resistance (open circuit); anything below 10k ohms indicates a short to ground.
3
Step 3: If the airbag module tests normal, inspect the wiring harness by disconnecting both ends (airbag side and control module side) and measure resistance from each wire to ground. Check for less than infinite resistance indicating a short in the harness. Pay special attention to areas where wiring passes through grommets or near metal edges.
4
Step 4: If wiring tests normal, measure the resistance across the airbag squib terminals with the connector disconnected (typically 2-3 ohms for most passenger airbags). If resistance is zero ohms or shows continuity to the airbag housing, the airbag module has an internal short and requires replacement.
5
Step 5: After repairs, reconnect all components, reconnect the battery, clear codes, and verify the airbag warning light turns off. Perform a test drive and re-scan to confirm the fault does not return and the airbag system is fully operational.
Estimated Repair Cost
$150 - $1,200
Parts + labor, varies by vehicle and location
This code indicates that the airbag control module has detected an abnormal electrical short to ground in the passenger-side airbag circuit. The airbag control module continuously monitors the resistance and continuity of all airbag circuits, and when it detects lower than expected resistance (typic...
The most common cause of B1938 (Air Bag Passenger Circuit Short To Ground) is: Damaged or chafed wiring harness under passenger seat or in door pillar causing wire insulation to contact ground
Typical repair costs for B1938 range from $150 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This is a critical safety fault that typically disables the passenger airbag entirely, meaning the airbag will not deploy in a collision and puts the passenger at severe risk of injury. The vehicle should not be driven with passengers until this fault is repaired, and diagnosis should be performed immediately by a qualified technician due to the risk of accidental deployment during improper handling.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1938 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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