Code Definition

B1389 — Oil Temperature Sensor Circuit Failure

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

About B1389

B1389 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 B1389 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.

B1389 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 monitors the oil temperature sensor circuit and sets DTC B1389 when the signal voltage falls outside the expected operating range or the circuit performance fails plausibility checks against other temperature inputs. This is a generic circuit failure code covering multiple specific conditions, including signal stuck at a fixed value, intermittent dropouts, or readings inconsistent with engine warm up behaviour. The oil temperature sensor uses a negative temperature coefficient thermistor; the module supplies a 5V reference and reads the signal voltage, expecting a smoot...

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