What does B2100 mean on a Ford?

B2100. Door Driver Key Cylinder Switch Failure. Applies to F-150, Explorer, Taurus with door key cylinders.

What causes B2100 on a Ford?

Worn driver door key cylinder switch Open or shorted cylinder switch circuit Water intrusion into the door latch Broken actuator linkage Corroded door harness connector

How do I fix B2100 on a Ford?

Test lock and unlock inputs from the driver key Inspect the latch and linkage Check the door harness boot for breaks Test switch continuity Replace the cylinder switch per findings

Code

B2100

Door Driver Key Cylinder Switch Failure

Category: Body
Severity: Body Warning Light
Applies to: F-150, Explorer, Taurus with door key cylinders
Related: No single generic twin. See OBD Codes List

Findings, check these first

Worn driver door key cylinder switch
Open or shorted cylinder switch circuit
Water intrusion into the door latch
Broken actuator linkage
Corroded door harness connector

Standard procedure

Test lock and unlock inputs from the driver key
Inspect the latch and linkage
Check the door harness boot for breaks
Test switch continuity
Replace the cylinder switch per findings

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: no source links are recorded for this entry.

Last updated 2026-09-25.

Report a correction for B2100. Include your vehicle, the issue and a source if you have one.

This fault is part of the Ford PATS and no-start codes guide. It covers the family and the order to check it.