Code Definition

B1491 — Ignition Cylinder Sensor Circuit Failure

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

About B1491

B1491 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.

When B1491 is stored, the module has detected a sensor-related fault — the reported value from the named sensor is out of spec.

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.

B1491 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 Ignition Cylinder Sensor on Ford vehicles, also referred to as the PATS transceiver coil or key transponder antenna, is a small ring shaped coil that sits around the ignition lock cylinder and forms part of the Passive Antitheft System. Its job is to read the encrypted RF signal from the chip inside the ignition key and pass that signal to the PATS module, BCM, or PCM during the start sequence. Code B1491 sets when the controlling module detects an electrical fault in the sensor circuit, such as an open, short, or out of range signal during key authentication. When this code is active the ...

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