B051C
Left side assist step position sensor circuit fault
What it means
B051C. Left side assist step position sensor circuit fault. The assist step module cannot confirm the running board position and the body warning light comes on.. This Chevy-enhanced code applies to Chevrolet, GMC, Buick, Cadillac, Pontiac, Oldsmobile and Saturn models that use this code.
Findings, check these first
- Faulty left side assist step position sensor
- Sensor harness open or shorted
- Poor electrical connection at the sensor
- Faulty assist step control module
Standard procedure
- Confirm the code with a scan tool
- Inspect the sensor and its connector for damage
- Test the sensor circuit for opens, shorts and poor connections
- Command the running board with the scan tool and watch the position data
- Replace the sensor or assist step control module only after circuit tests pass
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Sources and review
Review: qualified. Read the source limits below.
- B051C CHEVROLET Code: Meaning, Causes, and Symptoms | OBD2 Codes - OBD2 Codes
live reference page (obd2-codes.co)
Supports: CHEVROLET and GM-family meaning and likely causes for B051C
Fetched directly. B051C reads "Left Side Assist Step Position Sensor Circuit".
Last updated 2026-10-02.
Report a correction for B051C. Include your vehicle, the issue and a source if you have one.