Code Definition

B2645 — Ambient light sensor circuit

System: Body  |  Type: Generic (OBD-II Standard)  |  Make: Holden

About B2645

B2645 is a generic (obd-ii standard) body diagnostic trouble code recorded for Holden vehicles. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B2645 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.

Because B2645 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The Body Control Module (BCM) monitors the ambient light sensor circuit to judge how bright it is outside and to control the automatic headlamps and the dimming of the instrument and interior lighting. The sensor is usually a photodiode mounted on top of the dash that returns a varying voltage to the BCM as light levels change. DTC B2645 sets when the BCM sees an open circuit, a short to ground, or a short to voltage on that sensor circuit, or a signal that stays fixed and out of its normal range. When the code is set the automatic headlights may switch on or off at the wrong times, or the das...

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