B0021 Code: Meaning, Causes, and Symptoms | OBD2 Codes
B0021 – Left Curtain Deployment Control 1
B0021 Possible Symptoms
Air Bag Warning Light ON
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
The 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.