Code Definition

B1B40 (12-AF) — Left Front Outer Sensor

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

About B1B40

B1B40 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 B1B40 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.

B1B40 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 Parking Aid Module (PAM) monitors each ultrasonic sensor in the front and rear bumper arrays by supplying a switched feed and reading a return signal that varies as the sensor transmits an ultrasonic burst and listens for the reflected echo. DTC B1B40:12 is set when the PAM detects a short to battery (higher than expected voltage) on the left front outer ultrasonic sensor circuit. The left front outer sensor sits at the outer end of the front bumper array and is responsible for obstacle detection on the left front corner of the vehicle during low speed manoeuvring. The AF subcode is a Ford...

Join TaT to view the complete code information and diagnostic details.

Quick Facts