Code Definition

B1331 — Decklid Ajar Rear Door Circuit Failure

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

About B1331

B1331 is a manufacturer-specific body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1331 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.

B1331 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 decklid or rear door ajar switch is a contact switch mounted in the trunk lid latch or rear door jamb that informs the Body Control Module (BCM) when the trunk or rear door is open. Most systems use a switch that grounds the BCM input when the trunk lid is open and breaks the circuit when latched. DTC B1331 is set when the BCM detects an electrical fault on the ajar circuit, typically an open circuit or signal that does not match expected behaviour, preventing reliable detection of trunk or rear door state. Symptoms include the trunk ajar warning illuminating constantly or remaining off wh...

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