B0021 - Left Curtain Deployment Control 1
B0021 Possible Causes
- Faulty Driver Side Air Curtain
- Driver Side Air Curtain harness is open or shorted
- Driver Side Air Curtain circuit poor electrical connection
How do I fix code B0021?Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.
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Cost of diagnosing the B0021 code
Labor: 1.0The cost of diagnosing the B0021 code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
When is the code detected?If the Restraints Control Module (RCM) detects a short between the driver side air curtain circuits and the circuits of another SRS component, it sets this Diagnostic Trouble Code (DTC) and the DTC of the corresponding SRS component.
- Air Bag Warning Light ON
B0021 DescriptionThe Restraints Control Module (RCM) monitors all deployable device and sensor circuits for a signal cross coupled (short) between circuits. If the RCM detects a short between the circuits of one device and another device, it will store a DTC for each of the signal cross coupled faults in memory. The RCM sends a message to the Instrument Panel Cluster (IPC) to illuminate the air bag warning indicator. When a normal loop fault is present (one loop is either shorted to battery/ground, open circuit or low resistance), then signal cross coupled diagnostics will not be active. Once the normal loop fault is repaired, then the signal cross coupled diagnostics will resume.
More InformationNeed more information on how to fix the B0021 code?
Get Access to Factory Service Manuals
Information for specific makes
- B0021 BUICK Passenger Seat Side Air Bag Deployment Loop
- B0021 CADILLAC Passenger Seat Side Air Bag Deployment Loop
- B0021 CHEVROLET Passenger Seat Side Air Bag Deployment Loop
- B0021 FORD Left Curtain Deployment Control 1
- B0021 GMC Passenger Seat Side Air Bag Deployment Loop
- B0021 LINCOLN Left Curtain Deployment Control 1
- B0021 MERCURY Left Curtain Deployment Control 1
- B0021 PONTIAC Passenger Seat Side Air Bag Deployment Loop
- B0021 SATURN Passenger Seat Side Air Bag Deployment Loop
Precautions for SRS “AIR BAG” and “SEAT BELT PRE-TENSIONER” Service
- Never probe the electrical connectors on air bag, side air curtain modules or seat belts.
- Never disassemble or tamper with safety belt buckle/retractor pretensioners, adaptive load limiting retractors, safety belt inflators, or probe the electrical connectors.
- Do not use electrical test equipment to check SRS circuits unless instructed to in this Service Manual.
- Before servicing the SRS, turn ignition switch OFF, disconnect both battery cables and wait at least 3 minutes. For approximately 3 minutes after the cables are removed, it is still possible for the air bag and seat belt pre-tensioner to deploy. Therefore, do not work on any SRS connectors or wires until at least 3 minutes have passed.
Need more help?Get the B0021 code diagnosed by a professional: Find a repair shop in your area
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