Code Definition

B1013 (23) — Rear window demister switch circuit malfunction

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

About B1013

B1013 is a manufacturer-specific body diagnostic trouble code recorded for Mazda vehicles. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1013 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.

B1013 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 rear window demister (defogger) switch input circuit to detect when the driver requests rear defogger operation. The switch is a momentary input that pulls the signal line either to ground or to voltage depending on the circuit design, and the BCM uses the resulting signal to energise the rear defogger relay and supply power to the grid element. DTC B1013 is set when the BCM detects that the switch circuit signal is out of the expected voltage range — stuck continuously active, permanently open, or showing shorted voltage levels that cannot represen...

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