Code Definition

B1859 — Climate Control A/C Pressure Switch Circuit Open

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

About B1859

B1859 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 B1859 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit.

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.

B1859 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 the A/C Pressure Switch circuit as part of the climate control system. DTC B1859 is set when the BCM detects an open circuit condition on the A/C pressure switch signal, meaning the expected continuity between the switch and the module cannot be established. The A/C pressure switch provides a feedback signal that allows the BCM to enable or disable compressor operation based on refrigerant pressure, protecting the compressor from damage at extreme high or low pressure. When this code is set, the air conditioning compressor clutch typically will not engage...

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