Code Definition

B1D21 (62) — Remote Control Switch – Signal Compare Failure

System: Body  |  Type: Manufacturer-Specific  |  Make: Ford

About B1D21

B1D21 is a manufacturer-specific body diagnostic trouble code recorded for Ford vehicles. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

B1D21 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The Body Control Module (BCM) monitors signals from the keyless entry remote control transmitter and compares the received data against stored authentication codes, timing windows, and expected message structure. DTC B1D21:62 is set when the BCM detects that the incoming remote control switch signal does not match its expected pattern, indicating a signal comparison failure. This can be caused by a weak or failing transmitter, a damaged receiver circuit, RF interference, or a programming mismatch between the remote and the BCM. When this code is set the driver typically experiences intermitten...

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