What it means
B0020 indicates an electrical fault in the passenger (right-front) Stage-2 deployment loop. Factory documentation shows the SDM sets specific sub-codes based on the fault type and duration (e.g., :01 short-to-B+ for ≥2 s, :02 short-to-GND for ≥2 s, :04 open for ≥2 s, :0D resistance above threshold for ≥2 s, :0E resistance below threshold for ≥2 s). Saab WIS provides similar criteria and explicit resistance thresholds for the B0019/B0020 pair. Saab Wisonline
Symptoms
- Airbag/SRS lamp on; B0020 stored (often with symptom byte).
- Passenger frontal airbag Stage-2 may be disabled until corrected. NHTSA
Severity / priority
High (safety-critical). A Stage-2 loop fault can compromise full-force deployment in higher-severity collisions. Resolve and verify promptly. NHTSA
Common causes
- Open/high resistance from broken/chafed wiring, poor pin tension, corrosion; or low resistance/shorts to B+ or ground in the RF Stage-2 high/low circuits. Saab Wisonline
- Connector issues (shorting bar faults, backed-out pins) in the IP/airbag connectors.
- Less common: internal fault of the RF airbag Stage-2 inflator or the SDM/RCM.
- GM PI/TSB notes show B0020 among intermittent SIR codes often tied to connection integrity. NHTSA
Diagnostic notes
- Use an SRS-capable scan tool to read B0020 and its symptom byte; capture freeze-frame; check for companion codes (e.g., B0019 Stage-1 RF loop). Follow OEM SRS safety procedures. Saab Wisonline
- Perform connector and harness inspection (RF airbag/IP harness/intermediate connectors). On some platforms, under-dash/seat movement and vibration lead to intermittent opens/shorts.
- Conduct pinpoint tests: verify short-to-B+, short-to-GND, and open/high/low resistance conditions against factory thresholds (Saab WIS shows >~4.2 Ω for ≥2 s → :0D; open for ≥2 s → :04; etc.). Saab Wisonline
Possible fixes
- Repair/replace damaged conductors and terminals; correct pin fit and corrosion; restore proper harness routing. Saab Wisonline
- If indicated by testing, replace the RF airbag module (Stage-2 inflator); evaluate the SDM/RCM only after the loop hardware proves good.
- Clear DTCs and re-verify with a functional check and a rescan. NHTSA
Sources
GM preliminary information/TSB (PIT5564A): lists B0019/B0020 among common/intermittent SIR DTCs with resistance-above/below-threshold symptom bytes. NHTSA
Saab WIS factory page “DTC B0019 or B0020” with explicit fault criteria and thresholds (short-to-voltage/ground, open, high-resistance). Saab Wisonline
Aftermarket technical mapping of B0020 symptom-byte definitions (for quick reference of :01/:02/:04/:0D/:0E). MyAirbags Blog