Code Definition

B1390 — Oil Temperature Sensor Circuit Short To Ground

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

About B1390

B1390 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 B1390 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) 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.

B1390 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 signal voltage and sets DTC B1390 when the signal voltage is pulled below the expected operating range, indicating a short to ground on the signal circuit. The oil temperature sensor uses a negative temperature coefficient thermistor; under normal operation the signal voltage sits between approximately 0.3V when fully hot and 4.8V when cold, so a sustained reading at or near 0V is interpreted by the module as a short to ground because no plausible oil temperature would produce that reading. The module relies on this temperature value ...

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