The body control module sees a fault in the rear defog switch circuit
What it means
B1013. The body control module sees a fault in the rear defog switch circuit. The rear window defroster may not turn on or may not shut off.
Findings, check these first
- Faulty rear defog switch
- Open or shorted defog switch wiring
- Poor connection at the switch or body control module
- Stuck rear defog relay
- Faulty body control module
Standard procedure
- Confirm the code and operate the rear defog switch
- Inspect the switch and its connector for damage
- Test the switch signal circuit for an open or short
- Check the defog relay and its control circuit
- Replace the failed switch or relay after testing
Code lookup
Type a code above, or start from a symptom or a common code.
Press / to jump to the box. Ford-enhanced powertrain, body, chassis and network codes. Generic P0xxx codes live on OBD Codes List.
Sources and review
Review: checked against the recorded source material.
- B1013 FORD: Code Meaning, Causes, Symptoms, & Tech Notes | Engine-Codes.com
archived reference page (engine-codes.com via Wayback Machine)
Supports: code identity, Ford meaning and possible causes
Fetched directly. Ford title, meaning and causes match the catalog record. Model and year fitment remain curator claims.
- B1013 FORD Heater Rear Defog Switch | AutoCodes.com
archived reference page (autocodes.com via Wayback Machine)
Supports: corroboration of Ford meaning and causes
Same Ford text as the engine-codes page (both sites share one publisher).
Last updated 2026-09-26.
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