B1938 code definition
The B1938 code is manufacturer-specific (in this case General Motors) body code related to air bags. In this case, it means that the engine control module (ECM) has detected a fault with the passenger-side air bag.
What the B1938 code means
A code B1938 will be stored when the ECM has detected a resistance signal other than 1.4-2.9 ohms in the passenger-side air bag module circuit. In addition, the wiring harness between the passenger-side air bag module and SAS control module may have noted a fault or malfunction.
What causes the B1938 code?
Several problems may cause a B1938 code including:
- Open or short circuit in the wiring harness between the passenger-side air bag module
- Passenger-side air bag module malfunction
- SAS control module malfunction
What are the symptoms of the B1938 code?
Symptoms of a B1938 code may include:
- The check engine or service engine soon light may illuminate
- Air bag light may incorrectly illuminate
- Air bag light may flash
- Passenger-side air bag may not inflate during a crash
- There may be no symptoms other than a stored B1938 code
How does a mechanic diagnose the B1938 code?
A mechanic may use several methods to diagnose a B1938 trouble code, including:
- Utilize an OBD-II scanner to check for a stored B1938 trouble code
- Visually inspect the system for obvious signs of damage or wear
- Inspect the passenger-side air bag module
- Inspect the passenger-side air bag module connector
- Check to see if the malfunction is in the passenger-side air bag module or related wiring harness
- Inspect the SAS control module
Common mistakes when diagnosing the B1938 code
Note that listed detection conditions are for understanding the DTC outline before performing an inspection. Performing an inspection according to only the detection conditions may cause injury due to an operating error, or damage the system. When performing an inspection, it is recommended to always follow the inspection procedure.
How serious is the B1938 code?
Because a vehicle’s safe driving operation can be impacted due to faults that store a B1938 code, this code is considered a potentially serious code. When this code appears, it is recommended to immediately take your vehicle to your local service center or mechanic for repair and diagnosis.
What repairs can fix the B1938 code?
Several repairs can fix a B1938 trouble code and include:
- Repair or replace damaged, shorted, or corroded wiring or related electrical components
- Replace damaged or defective SAS control module
- Replace damaged or defective passenger-side air bag wiring harness
- Replace damaged or defective passenger-side air bag module
Additional information related to a B1938 code
Improperly handling a vehicle’s air bag system components can accidentally deploy the air bag modules and pre-tensioner seat belts, which can seriously injure you anyone who may be around you. Always read the service warnings and cautions before handling any air bag system components.
Remember, anything related to air bags can be both difficult and dangerous, and is often best left to professionals for diagnosis and repair. If making any repairs yourself, it is recommended to take care with the air bags when removed from the vehicle and store in a safe place.
Need help with a B1938 code?
YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.
This article originally appeared on YourMechanic.com as B1938 OBD-II Trouble Code: Air Bag Passenger Circuit Short to Ground and was authored by Parker Hill.