Code Definition

B2381 — Heater Coolant Temp sensor circuit Open

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

About B2381

B2381 is a generic (obd-ii standard) body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B2381 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit; and 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 B2381 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 heater coolant temperature sensor is mounted in or near the heater core feed pipe and provides the climate control module with a temperature signal that represents the coolant entering the heater core. The climate control module uses this signal to determine when heated air can be supplied to the cabin, to control the blower delay on cold starts, and to manage the cabin temperature ramp during engine warm up. DTC B2381 sets when the climate control module detects the heater coolant temperature sensor signal voltage stays at or near the pull up reference voltage, indicating an open circuit ...

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