Code Definition

B1858 — Climate Control A/C Pressure Switch Circuit Failure

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

About B1858

B1858 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 B1858 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

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.

B1858 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 B1858 is set when the BCM detects that the A/C pressure switch signal is outside expected parameters, typically indicating an open or shorted circuit between the switch and the module. 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 system may operate erratically or fail to ...

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

Quick Facts